Charles Spurgeon Commentary 1 Samuel 20:19-23

"And when thou hast stayed three days, thou shalt go down quickly, and come to the place where thou didst hide thyself when the business was in hand, and shalt remain by the stone Ezel. And I will shoot three arrows on the side thereof, as though I shot at a mark. And, behold, I will send the lad, [saying], Go, find the arrows. If I say unto the lad, Behold, the arrows are on this side of thee; take them, and come; for there is peace to thee and no hurt, as Jehovah liveth. But if I say thus unto the boy, Behold, the arrows are beyond thee; go thy way; for Jehovah hath sent thee away. And as touching the matter which thou and I have spoken of, behold, Jehovah is between thee and me for ever." — 1 Samuel 20:19-23 (ASV)

Thus, arrangements were made to let David know if he was in danger. Love is thoughtful; love seeks to keep its object out of harm's way. Therefore, if we love anyone, let us try to preserve them from sin, let us endeavor to warn them when temptation is near, that they may not fall by the hand of the enemy.