The men of David said to him, Behold, the day of which Yahweh said to you, Behold, I will deliver your enemy into your hand, and you shall do to him as it shall seem good to you. Then David arose, and cut off the skirt of Saul's robe secretly.
It is interesting that God prevented David’s enemies from assassinating him later when he was Israel’s king (cf. Galatians 6:7). Compare also Jesus’ refusal to take vengeance on His enemies (Luke 23:34).