Psalm 104:2

And David came to Saul, and stood before him
As a servant, and ministered to him in the way, and for the purpose for which he was sent:

and he loved him greatly;
being a comely person, and a well behaved youth, and especially as he was serviceable to him with his music, in driving away melancholy from him:

and he became his armourbearer;
that is, he appointed him to this office, though we never read that he exercised it; nor did he go with Saul in this capacity to the battle related in the following chapter: it may be literally rendered: "and he was to him a bearer of vessels", or "instruments" ^F17; and Abarbinel thinks this is to be understood not of instruments of war, but of instruments of music to play with; which he brought in and bare before him when he went in to the king.