Narrated 'Um al-'Ala:

An Ansari woman who gave the pledge of allegiance to the Prophet that the Ansar drew lots concerning the dwelling of the Emigrants. 'Uthman bin Maz'un was decided to dwell with them (i.e. Um al-'Ala's family), 'Uthman fell ill and I nursed him till he died, and we covered him with his clothes. Then the Prophet came to us and I (addressing the dead body) said, "O Abu As-Sa'ib, may Allah's Mercy be on you! I bear witness that Allah has honored you." On that the Prophet ﷺ said, "How do you know that Allah has honored him?" I replied, "I do not know. May my father and my mother be sacrificed for you, O Allah's Apostle! But who else is worthy of it (if not 'Uthman)?" He said, "As to him, by Allah, death has overtaken him, and I hope the best for him. By Allah, though I am the Apostle of Allah, yet I do not know what Allah will do to me," By Allah, I will never assert the piety of anyone after him. That made me sad, and when I slept I saw in a dream a flowing stream for 'Uthman bin Maz'un. I went to Allah's Apostle and told him of it. He remarked, "That symbolizes his (good) deeds."

حَدَّثَنَا مُوسَى بْنُ إِسْمَاعِيلَ، حَدَّثَنَا إِبْرَاهِيمُ بْنُ سَعْدٍ، أَخْبَرَنَا ابْنُ شِهَابٍ، عَنْ خَارِجَةَ بْنِ زَيْدِ بْنِ ثَابِتٍ، أَنَّ أُمَّ الْعَلاَءِ ـ امْرَأَةً مِنْ نِسَائِهِمْ بَايَعَتِ النَّبِيَّ ﷺ ـ أَخْبَرَتْهُ أَنَّ عُثْمَانَ بْنَ مَظْعُونٍ طَارَ لَهُمْ فِي السُّكْنَى حِينَ اقْتَرَعَتِ الأَنْصَارُ عَلَى سُكْنَى الْمُهَاجِرِينَ، قَالَتْ أُمُّ الْعَلاَءِ فَاشْتَكَى عُثْمَانُ عِنْدَنَا، فَمَرَّضْتُهُ حَتَّى تُوُفِّيَ، وَجَعَلْنَاهُ فِي أَثْوَابِهِ، فَدَخَلَ عَلَيْنَا النَّبِيُّ ﷺ فَقُلْتُ رَحْمَةُ اللَّهِ عَلَيْكَ أَبَا السَّائِبِ، شَهَادَتِي عَلَيْكَ لَقَدْ أَكْرَمَكَ اللَّهُ. فَقَالَ النَّبِيُّ ﷺ " وَمَا يُدْرِيكِ أَنَّ اللَّهَ أَكْرَمَهُ ". قَالَتْ قُلْتُ لاَ أَدْرِي بِأَبِي أَنْتَ وَأُمِّي يَا رَسُولَ اللَّهِ فَمَنْ قَالَ " أَمَّا هُوَ فَقَدْ جَاءَهُ وَاللَّهِ الْيَقِينُ، وَاللَّهِ إِنِّي لأَرْجُو لَهُ الْخَيْرَ، وَمَا أَدْرِي وَاللَّهِ وَأَنَا رَسُولُ اللَّهِ مَا يُفْعَلُ بِي ". قَالَتْ فَوَاللَّهِ لاَ أُزَكِّي أَحَدًا بَعْدَهُ قَالَتْ فَأَحْزَنَنِي ذَلِكَ فَنِمْتُ فَأُرِيتُ لِعُثْمَانَ بْنِ مَظْعُونٍ عَيْنًا تَجْرِي، فَجِئْتُ رَسُولَ اللَّهِ ﷺ فَأَخْبَرْتُهُ. فَقَالَ " ذَلِكَ عَمَلُهُ ".