Sahih Muslim Book 38, Hadith Number 6684.

Zaid b. Thabit reported that Allah’s Apostle (may peace be upon him) set out for Uhud. Some of those persons who were with them came back. The Companions of Allah’s Apostle (may peace be upon him) were divided in two groups. One group said: We would kill them, and the other one said: No, this should not be done, and it was on this occasion that this verse was revealed: “Why should you, then, be two parties in relation to hypocrites?” (iv. 88).