Abu Saeed Khudri reported,
And in it, then He will say, "Go back, and whoever you find in his heart the weight of an atom of good, bring him out." So they will bring out a great many people. Then he mentioned the hadith… Then they will say, "Our Lord, we have not left anyone in it."Abu Saeed used to say, "If you do not believe me regarding this hadith, then recite, 'Indeed, Allah does not wrong even the weight of an atom, and if there is a good deed, He multiplies it and gives from Himself a great reward.' [Nisa 4:40]"So the prophets, the angels, and the believers will intercede, and the Almighty will say, "My intercession remains." Then He will take a handful from the Fire and bring out people who have been burnt to charcoal. They will be cast into a river at the entrances of Paradise called the Water of Life, and they will sprout on its banks as a seed sprouts in the silt left by a flood. You have seen it beside a rock or beside a tree, the part facing the sun is green and the part in the shade is white. They will come out like pearls, with seals placed around their necks. Then they will enter Paradise.The people of Paradise will say, "These are the freed ones of the Most Merciful. He has admitted them to Paradise without any deed they performed or any good they sent forth."It will be said to them, "You have what you have seen, and the like of it along with it."
Azami 16192
Sahihعن أبي سعيد الخدري قال
وفيه: ثم يقول: ارجعوا فمن وجدتم في قلبه مثقال ذرة من خير، فأخرجوه فيخرجون خلقا كثيرا، فذكر الحديث… ثم يقول: ربنا لم نذر فيها أحدا. وكان أبو سعيد يقول: فإن لم تصدقوني بهذا الحديث فاقرؤوا: {إن الله لا يظلم مثقال ذرة وإن تك حسنة يضعفها ويؤت من لدنه أجرا عظيما} [النساء: ٤٠] فيشفع النبيون والملائكة والمؤمنون فيقول الجبار: بقيت شفاعتي، فيقبض قبضة من النار، فيخرج أقواما قد امتحشوا فيلقون في نهر بأفواه الجنة، يقال له: ماء الحياة، فينبتون في حافتيه كما تنبت الحبة في حميل السيل، قد رأيتموها إلى جانب الصخرة، وإلى جانب الشجرة، فما كان إلى الشمس منها كان أخضر، وما كان منها إلى الظل كان أبيض، فيخرجون كأنهم اللؤلؤ فيجعل في رقابهم الخواتيم، فيدخلون الجنة، فيقول أهل الجنة: هؤلاء عتقام الرحمن أدخلهم الجنة بغير عمل عملوه، ولا خير قدموه، فيقال لهم: لكم ما رأيتم، ومثله معه.
Bukhari narrated it in the Book of Monotheism (7439), and Muslim in the Book of Faith (183), both through the route of Zayd bin Aslam, from Ata bin Yasar, from Abu Saeed, who mentioned it in a lengthy hadith. This is the wording of Bukhari.The summary is that in the hadith of Abu Saeed Khudri there occurs some rearrangement of order, and some abridgment and elaboration, just as the hadith of Anas was narrated with the same meaning. The gist of it is that the Prophet ﷺ intercedes three times, and on the fourth occasion he says, "O Lord, grant me permission regarding whoever said, 'There is no god but Allah.'" Allah 
then says, "That is not for you, but by My might, My greatness, My majesty, and My sublimity, I will surely bring out whoever said, 'There is no god but Allah.'"This means that Allah , by His mercy and grace, brings out of the Fire everyone who acknowledged monotheism, even if he never performed a single good deed at all, and this applies to all nations, like the man who instructed that he be burned after his death because of the abundance of his sins, yet he feared Allah, may He be exalted, believing that He would punish him severely.The Prophet ﷺ then informs us that no one remains in the Fire afterward except those detained there by the Quran, meaning those for whom eternal punishment has become obligatory, as stated in the tafsir of Qatada, namely the disbelievers, the polytheists, and the hypocrites. As Allah, may He be exalted, said, "Indeed, those who disbelieved and died while they were disbelievers, upon them is the curse of Allah and the angels and the people, all together, abiding therein eternally. The punishment will not be lightened for them, nor will they be reprieved" [Baqarah 2:161–162]."Indeed, whoever associates partners with Allah, Allah has forbidden him Paradise, and his refuge is the Fire. And there are no helpers for the wrongdoers" [Maidah 5:72]."Indeed, Allah does not forgive association with Him, but He forgives what is less than that for whom He wills. And whoever associates partners with Allah has certainly strayed far astray" [Surah Nisa 4:116].And He said concerning the hypocrites, "Indeed, the hypocrites will be in the lowest depths of the Fire, and you will never find for them a helper" [Surah Nisa 4:145].As for what appears in the hadith of Anas, where he said, "I do not know whether it was on the third or the fourth occasion that he said, 'I will say, O my Lord, no one remains in the Fire except those detained there by the Quran,'" his mention of "the fourth" means after the fourth occasion.As for the period after the sending of the Prophet ﷺ, belief in his message must accompany the acknowledgment of monotheism, as it has been established as sahih from the Prophet ﷺ that he said, "If Musa were alive, nothing would be open to him except to follow me."Praise be to Allah for His enabling grace.