1 Samuel 18:4

“And Jonathan stripped himself of the robe that [was] upon him, etc.] As a token of his hearty love and true friendship, and that David might appear at court not in the habit of a shepherd, but in that of a prince: and gave it to David, and his garments; his other garments besides his robe, and so clothed him from tip to toe, and which fitted him; for as there was a similarity in their souls, and the disposition of them, so in the make and hulk of their bodies, and in the stature of them: even to his sword, and to his bow, and to his girdle; these he gave him to accoutre himself with, that he might appear as a soldier, as well as like a prince, and as another Jonathan, or rather the same;…”

“Jonathan stripped himself of the robe that was upon him, and gave it to David--To receive any part of the dress which had been worn by a sovereign, or his eldest son and heir, is deemed, in the East, the highest honor which can be conferred on a subject (see on Est 6:8). The girdle, being connected with the sword and the bow, may be considered as being part of the military dress, and great value is attached to it in the East.”

“stripped himself: Presents of clothes or rich robes, as tokens of respect or friendship, are frequent in the East. Gen 41:42; Est 6:8, Est 6:9; Isa 61:10; Luk 15:22; Co2 5:21; Phi 2:7, Phi 2:8 1 Kings (1 Samuel) 18:5”

“As a sign and pledge of his friendship, Jonathan gave David his clothes and his armour. Meil, the upper coat or cloak. Maddim is probably the armour coat (vid., Sa1 17:39). This is implied in the word ועד, which is repeated three times, and by which the different arms were attached more closely to מדּיו. For the act itself, compare the exchange of armour made by Glaucus and Diomedes (Hom. Il. vi. 230). This seems to have been a common custom in very ancient times, as we meet with it also among the early Celts (see Macpherson's Ossian). 1 Kings (1 Samuel) 18:5”