The IVP Bible Background Commentary : New Testament

The InterVarsity Press Background Bible Commentary add helpful cultural insights for passages in the Bible.  An example is the notes on Luke 6.27-36.

6:27.  The Old Testament specifically commanded love of neighbor (Lev 19:18), but no one commanded love of enemies.
6:28.  Although Jesus (23:34) and his followers (Acts 7:60) practiced this rule of blessing and praying for enemies, prayers for vindication by vengeance were common in the Old Testament (2 Chron 24:22; Ps 137:7–9; Jer 15:15; cf. Rev 6:10) and in ancient execration (magical curse) texts.
6:29.  The blow on the right cheek was the most grievous insult in the ancient Near East. The clothing in the verse refers to the outer and inner cloak, respectively; the poorest of people (like the average peasant in Egypt) might have only one of each; thus here Jesus refers, perhaps in hyperbolic images, to absolute nonresistance on one’s own behalf.
6:30.  Here Jesus may allude to beggars, quite common in the ancient East, and poorer people seeking loans. In Jewish Palestine beggars were usually only those in genuine need, and most were unable to work; farmers generally sought loans to plant crops. Jewish society emphasized both charity and responsibility.
6:31.  In its negative form (“Do not do to others what you do not want them to do to you”), this was a common ethical saying in the ancient world.
6:32–33.  Ideas like loving enemies and lending without hoping to receive again were unheard of, although many Pharisees advocated peace with the Roman state (at least, tolerating enemies in some sense).
6:34–35.  In the Roman world, interest rates sometimes ran as high as 48 percent, but the Old Testament forbade usury, or charging interest. Because many Jewish creditors feared that they would lose their investment if they lent too near the seventh year (when the law required cancellation of all debts), they stopped lending then, hurting the small farmers who needed to borrow for planting. Jewish teachers thus found a way to circumvent this law so the poor could borrow so long as they repaid. Jesus argues that this practice should not be necessary; those with resources should help those without, whether or not they would lose money by doing so.
Biblical laws about lending to the poor before the year of release (Deut 15:9; every seventh year debts were forgiven; cf. Lev 25) support Jesus’ principle here, but Jesus goes even farther in emphasizing unselfish giving. Although the law limited selfishness, Jesus looks to the heart of the law and advocates sacrifice for one’s neighbor. A good man’s “sons” were expected to exemplify their father’s character; thus God’s children should act like him.
6:36.  That human mercy should reflect God’s mercy became a common Jewish saying (e.g., the Letter of Aristeas 208; rabbis). “Merciful” may reflect the same Aramaic word translated “perfect” in Matthew 5:48.
6:37.  “Judge,” “condemn” and “pardon” are all the language of the day of judgment, prefigured in God’s current reckonings with his people (e.g., on the Day of Atonement).
6:38.  The image here is of a measuring container into which as much grain as possible is packed; it is then shaken to allow the grain to settle, and more is poured in till the container overflows. Pouring it “into the lap” refers to the fold in the garment used as a pocket or pouch. Because Jewish people sometimes used “they” as a way of avoiding God’s name, here “they will pour” (NASB) may mean that God will do it; or the idea may be that God will repay a person through others. The Old Testament often speaks of God judging people according to their ways (e.g., Is 65:7). Proverbs and other texts speak of his blessings toward the generous (e.g., Deut 15:10; Prov 19:17; 22:9; 28:8).

Keener, C. S., & InterVarsity Press. (1993). The IVP Bible Background Commentary : New Testament (Lk 6:27–38). Downers Grove, Ill.: InterVarsity Press.

 This is in contrast with a more traditional commentary like The Bible Exposition Commentary.

Luke 6. 27-38

 We must not look at these admonitions as a series of rules to be obeyed. They describe an attitude of heart that expresses itself positively when others are negative, and generously when others are selfish, all to the glory of God. It is an inner disposition, not a legal duty. We must have wisdom to know when to turn the other cheek and when to claim our rights (John 18:22–23; Acts 16:35–40). Even Christian love must exercise discernment (Phil. 1:9–11).

Two principles stand out: we must treat others as we would want to be treated (Luke 6:31), which assumes we want the very best spiritually for ourselves; and we must imitate our Father in heaven and be merciful (Luke 6:36). The important thing is not that we are vindicated before our enemies but that we become more like God in our character (Luke 6:35). This is the greatest reward anyone can receive, far greater than riches, food, laughter, or popularity (Luke 6:24–26). Those things will one day vanish, but character will last for eternity. We must believe Matthew 6:33 and practice it in the power of the Spirit.

Wiersbe, W. W. (1996). The Bible Exposition Commentary (Lk 6:20). Wheaton, Ill.: Victor Books.

1 Sam 26

1 Samuel
26.19  This is a fascinating  verse on many levels. I just with I understood all the dynamics of this exchange better.
"When Saul heard David's voice (for he could hardly have seen David, as the occurrence took place before daybreak, at the latest when the day began to dawn), and David had made himself known to the king in reply to his inquiry, David said, “Why doth my lord pursue his servant? for what have I done, and what evil is in my hand?” He then gave him the well-meant advice, to seek reconciliation for his wrath against him, and not to bring upon himself the guilt of allowing David to find his death in a foreign land. The words, “and now let my lord the king hear the saying of his servant,” serve to indicate that what follows is important, and worthy of laying to heart. In his words, David supposes two cases as conceivable causes of Saul's hostility: (1) if Jehovah hath stirred thee up against me; (2) if men have done so. In the first case, he proposes as the best means of overcoming this instigation, that He (Jehovah) should smell an offering. The Hiphil יָרַח only means to smell, not to cause to smell. The subject is Jehovah. Smelling a sacrifice is an anthropomorphic term, used to denote the divine satisfaction (cf. Gen_8:21). The meaning of the words, “let Jehovah smell sacrifice,” is therefore, “let Saul appease the wrath of God by the presentation of acceptable sacrifices.” What sacrifices they are which please God, is shown in Psa_51:18-19; and it is certainly not by accident merely that David uses the word minchah, the technical expression in the law for the bloodless sacrifice, which sets forth the sanctification of life in good works. The thought to which David gives utterance here, namely, that God instigates a man to evil actions, is met with in other passages of the Old Testament. It not only lies at the foundation of the words of David in Psa_51:6 (cf. Hengstenberg on Psalms), but is also clearly expressed in 2Sa_24:1, where Jehovah instigates David to number the people, and where this instigation is described as a manifestation of the anger of God against Israel; and in 2Sa_16:10., where David says, with regard to Shimei, that God had bade him curse him. These passages also show that God only instigates those who have sinned against Him to evil deeds; and therefore that the instigation consists in the fact that God impels sinners to manifest the wickedness of their hearts in deeds, or furnishes the opportunity and occasion for the unfolding and practical manifestation of the evil desire of the heart, that the sinner may either be brought to the knowledge of his more evil ways and also to repentance, through the evil deed and its consequences, or, if the heart should be hardened still more by the evil deed, that it may become ripe for the judgment of death. The instigation of a sinner to evil is simply one peculiar way in which God, as a general rule, punishes sins through sinners; for God only instigates to evil actions such as have drawn down the wrath of God upon themselves in consequence of their sin. When David supposes the fact that Jehovah has instigated Saul against him, he acknowledges, implicitly at least, that he himself is a sinner, whom the Lord may be intending to punish, though without lessening Saul's wrong by this indirect confession.
The second supposition is: “if, however, children of men” (sc., have instigated thee against me); in which case “let them be cursed before the Lord; for they drive me now (this day) that I dare not attach myself to the inheritance of Jehovah (i.e., the people of God), saying, Go, serve other gods.” The meaning is this: They have carried it so far now, that I am obliged to separate from the people of God, to fly from the land of the Lord, and, because far away from His sanctuary, to serve other gods. The idea implied in the closing words was, that Jehovah could only be worshipped in Canaan, at the sanctuary consecrated to Him, because it was only there that He manifested himself to His people, and revealed His face or gracious presence (vid., Psa_42:2-3; Psa_84:11; Psa_143:6.). “We are not to understand that the enemies of David were actually accustomed to use these very words, but David was thinking of deeds rather than words” (Calvin).
When Saul heard David's voice (for he could hardly have seen David, as the occurrence took place before daybreak, at the latest when the day began to dawn), and David had made himself known to the king in reply to his inquiry, David said, “Why doth my lord pursue his servant? for what have I done, and what evil is in my hand?” He then gave him the well-meant advice, to seek reconciliation for his wrath against him, and not to bring upon himself the guilt of allowing David to find his death in a foreign land. The words, “and now let my lord the king hear the saying of his servant,” serve to indicate that what follows is important, and worthy of laying to heart. In his words, David supposes two cases as conceivable causes of Saul's hostility: (1) if Jehovah hath stirred thee up against me; (2) if men have done so. In the first case, he proposes as the best means of overcoming this instigation, that He (Jehovah) should smell an offering. The Hiphil יָרַח only means to smell, not to cause to smell. The subject is Jehovah. Smelling a sacrifice is an anthropomorphic term, used to denote the divine satisfaction (cf. Gen_8:21). The meaning of the words, “let Jehovah smell sacrifice,” is therefore, “let Saul appease the wrath of God by the presentation of acceptable sacrifices.” What sacrifices they are which please God, is shown in Psa_51:18-19; and it is certainly not by accident merely that David uses the word minchah, the technical expression in the law for the bloodless sacrifice, which sets forth the sanctification of life in good works. The thought to which David gives utterance here, namely, that God instigates a man to evil actions, is met with in other passages of the Old Testament. It not only lies at the foundation of the words of David in Psa_51:6 (cf. Hengstenberg on Psalms), but is also clearly expressed in 2Sa_24:1, where Jehovah instigates David to number the people, and where this instigation is described as a manifestation of the anger of God against Israel; and in 2Sa_16:10., where David says, with regard to Shimei, that God had bade him curse him. These passages also show that God only instigates those who have sinned against Him to evil deeds; and therefore that the instigation consists in the fact that God impels sinners to manifest the wickedness of their hearts in deeds, or furnishes the opportunity and occasion for the unfolding and practical manifestation of the evil desire of the heart, that the sinner may either be brought to the knowledge of his more evil ways and also to repentance, through the evil deed and its consequences, or, if the heart should be hardened still more by the evil deed, that it may become ripe for the judgment of death. The instigation of a sinner to evil is simply one peculiar way in which God, as a general rule, punishes sins through sinners; for God only instigates to evil actions such as have drawn down the wrath of God upon themselves in consequence of their sin. When David supposes the fact that Jehovah has instigated Saul against him, he acknowledges, implicitly at least, that he himself is a sinner, whom the Lord may be intending to punish, though without lessening Saul's wrong by this indirect confession.
The second supposition is: “if, however, children of men” (sc., have instigated thee against me); in which case “let them be cursed before the Lord; for they drive me now (this day) that I dare not attach myself to the inheritance of Jehovah (i.e., the people of God), saying, Go, serve other gods.” The meaning is this: They have carried it so far now, that I am obliged to separate from the people of God, to fly from the land of the Lord, and, because far away from His sanctuary, to serve other gods. The idea implied in the closing words was, that Jehovah could only be worshipped in Canaan, at the sanctuary consecrated to Him, because it was only there that He manifested himself to His people, and revealed His face or gracious presence (vid., Psa_42:2-3; Psa_84:11; Psa_143:6.). “We are not to understand that the enemies of David were actually accustomed to use these very words, but David was thinking of deeds rather than words” (Calvin)."    K and D

1 Samuel 24-25

1 Samuel
24.13   Wickedness proceeds from the wicked.  
25.3  good understanding and beautiful appearance...but the man was harsh and evil...  How do two people like that end up together?
25.12  turned on their heels...  That would be an interesting expression to chase down sometime.  
25.32  David almost always saw God's mercy and appreciated it.