New Defender's Study Bible Notes
18:3 because he loved him. There is no hint here of a homosexual relationship between Jonathan and David, as some have contended. The love was one of friendship and deep admiration. David later had a number of wives and concubines, with many children. Jonathan also was head of his own “house” and had at least one son (I Samuel 20:15; II Samuel 9:3).
18:4 gave it to David. The practice of bestowing one’s garments and weapons upon another is known from archaeological discoveries to have symbolized the transfer of one’s position to another. Jonathan evidently knew that God through Samuel had chosen David to be the next king over Israel instead of himself (I Samuel 16:1,13), and he gladly accepted this as God’s will.
18:17 fight the LORD’s battles. Although Saul had promised his daughter to any man who would kill Goliath (I Samuel 17:25), his resentment of David led him to try to use this promise to get David slain (I Samuel 18:25).
18:30 more wisely. See also I Samuel 18:5 and 15. David not only possessed the strength and courage appropriate for a king, but also the wisdom, whereas Saul had been “greatly afraid” of Goliath (I Samuel 17:11) and had “done foolishly” (I Samuel 13:13) in the matter of offerings, as well as transgressing God’s commandment in the case of Agag (I Samuel 15:24).