Sahih Muslim Book - 1, Hadith - 457

و حَدَّثَنِي هَارُونُ بْنُ سَعِيدٍ الْأَيْلِيُّ حَدَّثَنَا ابْنُ وَهْبٍ قَالَ أَخْبَرَنِي مَالِكُ بْنُ أَنَسٍ عَنْ عَمْرِو بْنِ يَحْيَى بْنِ عُمَارَةَ قَالَ حَدَّثَنِي أَبِي عَنْ أَبِي سَعِيدٍ الْخُدْرِيِّ أَنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ يُدْخِلُ اللَّهُ أَهْلَ الْجَنَّةِ الْجَنَّةَ يُدْخِلُ مَنْ يَشَاءُ بِرَحْمَتِهِ وَيُدْخِلُ أَهْلَ النَّارِ النَّارَ ثُمَّ يَقُولُ انْظُرُوا مَنْ وَجَدْتُمْ فِي قَلْبِهِ مِثْقَالَ حَبَّةٍ مِنْ خَرْدَلٍ مِنْ إِيمَانٍ فَأَخْرِجُوهُ فَيُخْرَجُونَ مِنْهَا حُمَمًا قَدْ امْتَحَشُوا فَيُلْقَوْنَ فِي نَهَرِ الْحَيَاةِ أَوْ الْحَيَا فَيَنْبُتُونَ فِيهِ كَمَا تَنْبُتُ الْحِبَّةُ إِلَى جَانِبِ السَّيْلِ أَلَمْ تَرَوْهَا كَيْفَ تَخْرُجُ صَفْرَاءَ مُلْتَوِيَةً؟

It was narrated from Abu Sa'eed Al-Khudri that the Messenger of Allah (s.a.w) said: "Allah will admit the people of Paradise to Paradise and He will admit whomever He wills by His mercy. And He will admit the people of the Fire to the Fire. Then He will say: 'Look, and whomever you find with a mustard-seed's weight of faith in his heart, bring him out.' They will bring out people who have been burned, like charcoal, then they will be thrown into the River of Life (Al-Hayat) - or Rain (Al-Haya), from which they will emerge like seeds sprouting at the banks of the flood. Do you not see how they emerge yellow and curved?"