Bukhari

Hadith Commentary:
Muhammad ibn Bashar narrated to us, Muhammad ibn Abi ‘Adi narrated to us, from Shu‘bah, from Qatadah, from Abu Sadiq Naji Bakr ibn Qays, and from Abu Sa‘id al-Khudri, who said that the Noble Prophet (sallallahu alayhi wa sallam) said: Among the Children of Israel there was a man (his name is unknown) who had killed ninety-nine innocent people. Then he (became remorseful and) set out to ask about the matter.

He came to a dervish and asked him, “Is there any way for repentance to be accepted for this sin?” The dervish replied, “No.” Upon hearing this, he killed that dervish as well (thus completing one hundred murders).

Then he began to ask (others).

Eventually, a dervish told him, “Go to such-and-such a town.” (He had not even reached halfway when) death overtook him.

As he was dying, he turned his chest towards that town.

Then the angels of mercy and the angels of punishment began to dispute with each other (as to who should take him).

(Who should take him away?)

But Allah, the Exalted, commanded the town called Nasrah (to which he was going for repentance) to come closer to his corpse, and commanded the other town (from which he had set out) to move farther away from his corpse.

Then Allah, the Exalted, said to the angels, “Now measure the distance between the two.” (When it was measured,) that town (to which he was going for repentance) was found to be a handspan closer to his corpse, so he was forgiven.

Hadith Commentary:
1.
The word "monk" (rahib) indicates that this incident took place after Jesus (alayhis salam) was raised to the heavens, because monasticism (rahbaniyyah) began with those who were followers of Jesus (alayhis salam).

2.
Apparently, it seems that Allah Ta’ala, as a result of his repentance, forgave all his sins, even those sins that pertain to the rights of other people (huquq al-‘ibad), because Allah Ta’ala became pleased with this person, so those people whose rights he had usurped will also become pleased with him. Allah Ta’ala will Himself compensate the rightful claimants with a good reward from His own side and thus make them pleased. Accordingly, it is mentioned in a hadith:
“The Messenger of Allah (sallallahu alayhi wa sallam) supplicated to Allah Ta’ala in the latter part of the Day of ‘Arafah for the forgiveness of his ummah, so Allah Ta’ala granted him the honor of acceptance and said: ‘I have forgiven all their sins except those relating to the rights of others (huquq al-‘ibad). I will certainly take the right from the oppressor and give it to the oppressed.’ The Prophet (sallallahu alayhi wa sallam) again pleaded to Allah Ta’ala: ‘O Allah! If You will, please make the oppressed pleased by giving him a share from Paradise and forgive the oppressor.’ But at that time, this supplication was not accepted. Eventually, when he reached Muzdalifah in the morning and repeated this supplication, Allah Ta’ala accepted it, that is, He promised to forgive even the rights of others (huquq al-‘ibad).” (Sunan Ibn Majah, Kitab al-Manasik, Hadith: 3013)
However, ‘Allamah al-Albani (rahimahullah) has declared this hadith weak (da‘if).
(Da‘if Sunan Ibn Majah, Hadith: 651)

3.
In any case, there are a few conditions for the forgiveness of major sins (kabirah):
(a)
Major crimes should not be committed considering them to be lawful (halal).
(b)
He should perform abundant good deeds.
(c)
He should abandon those places and occasions where he used to commit sins, so that through this separation and distancing, his repentance becomes firm. In any case, those who hold the view that the repentance of a murderer of a believer is accepted have used this hadith as evidence.
And Allah knows best.