Adam Clarke on 1 Samuel 20:20

I will shoot three arrows - Jonathan intended that David should stay at the stone Ezel, where probably there was some kind of cave, or hiding place; that, to prevent all suspicion, he would not go to him himself, but take his servant into the fields, and pretend to be exercising himself in archery; that he would shoot three arrows, the better to cover his design; and that, if he should say to his servant, who went to bring back the arrows, "The arrows are on this side of thee," this should be a sign to David that he might safely return to court, no evil being designed; but if he should say, "The arrows are beyond thee," then David should escape for his life, Saul having determined his destruction.