Abu Saeed Khudri reported,

The Prophet ﷺ said that a man had killed ninety-nine people, and he began asking whether repentance was possible for him. He came to a monk and asked him.The monk said, "There is no repentance for you."So he killed the monk. Then he went on asking, and finally he set out from his village toward a village where righteous people lived. While he was still on the way, death overtook him, so he stretched his chest forward toward it and died. The angels of mercy and the angels of punishment disputed over him. He was found to be a handspan nearer to the righteous village, so he was counted among its people.This is the hadith of Muaz bin Muaz, and he added in it that Allah revealed to this village that it should move farther away and to that one that it should draw nearer.

Muslim 7010

Sahih

حدثنا محمد بن بشار حدثنا ابن أبي عدي حدثنا شعبة عن قتادة بهذا الإسناد نحو حديث معاذ بن معاذ وزاد فيه فأوحى الله إلى هذه أن تباعدي وإلى هذه أن تقربي

مسلم 7010صحيح
Contents
Reference
Commentary
Ayat
Collection
Sahih Muslim
Book
Tawba
Chapter
Acceptance of the repentance of a killer even if his killing was frequent
Numbering
Darussalam 7010
Muslim 7010