Narrated 'Abdullah bin Yazid:
from Zaid bin Thabit that he heard about this Ayah: Then what is the matter with you that you are divided into two parties about the hypocrites? (4:88) He said: "People among the Companions of the Prophet (ﷺ) returned on the Day of Uhud and there were two parties among them, a group who said: 'Kill them,' and a group that say not to. So Allah revealed this Ayah: Then what is the matter with you that you are divided into two parties about the hypocrites? (4:88) So he said: "Indeed it is Taibah (Al-Madinah). And he said: 'It expels filth from it just like the fire expels filth from iron.'" (DE)
English reference (DE): Vol. 5, Book 44, Hadith 3028 (DE)
Arabic reference (DE): Book 47, Hadith 3302 (DE)