Abu Saeed Khudri reported,
"I will only narrate to you what I heard from the Messenger of Allah ﷺ, what my ears heard and my heart retained.A servant killed ninety-nine souls, then the thought of repentance occurred to him. He asked about the most knowledgeable person on earth and was directed to a man. He came to him and said, 'I have killed ninety-nine souls. Is there any repentance for me?'The man replied, 'After killing ninety-nine souls?'So he drew his sword and killed him with it, completing one hundred. Then the thought of repentance occurred to him again, and he asked about the most knowledgeable person on earth. He was directed to another man, came to him, and said, 'I have killed one hundred souls. Is there any repentance for me?'The man said, 'Who could stand between you and repentance? Leave this wicked town you are in and go to the righteous town, the town of such and such, and worship your Lord there.'So he set out for the righteous town, but death overtook him on the way. The angels of mercy and the angels of punishment disputed over him.Iblis said, 'He belongs to me, for he never disobeyed me for a single hour.'The angels of mercy said, 'He left as a repentant man.'"Hammam said, Humayd Tawil narrated to me from Bakr bin Abdullah Muzani from Abu Rafi, "So Allah 
sent an angel to them, and they brought their dispute before him." Then he returned to the narration of Qatada, who said, "He said, 'See which of the two towns he was closer to, and assign him to its people.'"Qatada said, Hasan narrated to us, "When he sensed death, he strained himself forward. So Allah brought the righteous town nearer to him and moved the wicked town farther from him, and they assigned him to the people of the righteous town."
Azami 6833
Sahihعن أبي سعيد الخدري قال
لا أحدثكم إلا ما سمعت من رسول الله ﷺ سمعته أذناي، ووعاه قلبي: إن عبدا قتل تسعة وتسعين نفسا، ثم عرضت له التوبة، فسأل عن أعلم أهل الأرض، فدل على رجل، فأتاه فقال: إني قتلت تسعة وتسعين نفسا، فهل لي من توبة؟ قال: بعد قتل تسعة وتسعين نفسا؟ قال: فانتضى سيفه فقتله به، فأكمل به مئة، ثم عرضت له التوبة، فسأل عن أعلم أهل الأرض، فدل على رجل، فأتاه فقال: إني قتلت مئة نفس، فهل لي من توبة؟ فقال: ومن يحول بينك وبين التوبة، اخرج من القرية الخبيثة التي أنت فيها إلى القرية الصالحة قرية كذا وكذا، فاعبد ربك فيها، قال: فخرج إلى القرية الصالحة، فعرض له أجله في الطريق قال: فاختصمت فيه ملائكة الرحمة وملائكة العذاب قال: فقال إبليس: أنا أولى به، إنه لم يعصني ساعة قط. قال: فقالت ملائكة الرحمة: إن خرج تائبا. قال همام: فحدثني حميد الطويل، عن بكر بن عبد الله المزني، عن أبي رافع قال: فبعث الله عز وجل له ملكا فاختصموا إليه ثم رجع إلى حديث قتادة، قال: فقال: انظروا أي القريتين كان أقرب إليه، فألحقوه بأهلها. قال قتادة: فحدثنا الحسن قال: لما عرف الموت احتفز بنفسه، فقرب الله عز وجل منه القرية الصالحة، وباعد منه القرية الخبيثة، فألحقوه بأهل القرية الصالحة.
Bukhari narrated it in the Hadiths of the Prophets (3470) and Muslim in the Book of Repentance (2766), both from the hadith of Shuba, from Qatada, from Abu Siddiq Naji, from Abu Saeed Khudri, who said, and then he related it. Ahmad narrated it (11154) from the hadith of Hammam bin Yahya, from Qatada with his chain of transmission, and the wording given here is his because it is more complete. As for his saying, "from Abu Rafi, so Allah sent an angel to him," in Sahih Muslim it reads, "Then an angel came to them in human form, so they made him arbiter between them." And as for Hasan's saying, "he strained himself," this is found in the Sahihayn as, "When he was partway along the road, death overtook him, so he leaned forward with his chest, then died." This contains evidence that worship without knowledge is destructive.This story has also been narrated, in similar form, from Muawiya bin Abu Sufyan. Abu Yaala narrated it (7361) from Abu Hammam, who said, Walid bin Muslim narrated to us, saying, Abdul-Rahman bin Yazid bin Jabir narrated to me, saying, Ibn Abu Muhajir, or Abu Abd Rabb, narrated to me, Walid being uncertain which, he said, I heard Muawiya bin Abu Sufyan say, and then he related it. Ibn Abu Asim narrated it in Diyat (242, 321) through another route from Walid, without the uncertainty, stating it was Abu Abd Rabb. Tabarani narrated it in Kabir (19/369) through two other routes from Walid bin Muslim and Sadaqa bin Khalid, both of whom said, Ibn Jabir narrated to us, and then he related it with his chain of transmission, except that it contains "Ubayda bin Muhajir Abu Abd Rabb," which is an error.Ibn Abu Muhajir is Ubayda bin Abu Muhajir, whom no one deemed reliable except Ibn Hibban, so he is "unknown." Bukhari and Ibn Abu Hatim both gave him an entry but said nothing about him. Likewise Abu Abd Rabb, for no one deemed him reliable except Ibn Hibban. Haythami's statement in al-Majmu (10/211–212), "Tabarani narrated it with two chains, and the men of one of them are the men of the sahih narrations except for Abu Abd Rabb, who is trustworthy," relies on Ibn Hibban's assessment of reliability, and Ibn Hibban is well known for deeming unknown narrators reliable.The hadith belongs to Abu Saeed Khudri, but some narrators attributed it to Muawiya bin Abu Sufyan. As for what has been narrated from Anas bin Malik as a saying of the Prophet, "Allah has refused to grant repentance to one who kills a believer," its wording contains an objectionable element despite the soundness of its chain of transmission. Wahidi narrated it in his Tafsir, and Abu Bakr bin Mardawayh in his Tafsir, both through two different routes from Ibn Mubarak, from Sulayman Taymi, from Humayd, from Anas, who said, and then he related it.Except that Abu Bakr bin Mardawayh did not mention "Humayd" in it, and Diya, by his route, in al-Mukhtara (2/464), gives the wording as, "Ali has refused to grant repentance to one who kills a believer." It appears this is a corruption, and the correct wording, as I have stated, is "Allah has refused." The reason it is objectionable is that the door of repentance is open to everyone, and Allah accepts the repentance of His servant as long as death has not yet reached him.