Musnad Ahmad #435
Musnad Uthman ibn Affan
The Arabic includes the chain of narration (sanad) and the collector's commentary; the English translation shows the Prophet's words only.
حَدَّثَنَا عَفَّانُ، حَدَّثَنَا عَبْدُ الْوَارِثِ، حَدَّثَنَا أَيُّوبُ بْنُ مُوسَى، حَدَّثَنِي نُبَيْهُ بْنُ وَهْبٍ، أَنَّ عُمَرَ بْنَ عُبَيْدِ اللَّهِ بْنِ مَعْمَرٍ، رَمِدَتْ عَيْنُهُ وَهُوَ مُحْرِمٌ فَأَرَادَ أَنْ يُكَحِّلَهَا فَنَهَاهُ أَبَانُ بْنُ عُثْمَانَ رَضِيَ اللَّهُ عَنْهُ وَأَمَرَهُ أَنْ يُضَمِّدَهَا بِالصَّبِرِ وَزَعَمَ أَنَّ عُثْمَانَ رَضِيَ اللَّهُ عَنْهُ حَدَّثَ عَنْ رَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ أَنَّهُ فَعَلَ ذَلِكَ.
Nubaih bin Wahb narrated that the eye of `Umar bin Ubaidullah became inflamed when he was in ihram, and he wanted to apply kohl to it, but Aban bin `Uthman (رضي الله عنه) forbade him to do that and told him to apply aloes to it. He said that `Uthman (رضي الله عنه) narrated from the Messenger of Allah (ﷺ) that he had done that.
About Musnad Ahmad
This hadith is #435 from Musnad Ahmad, in the Book of Musnad Uthman ibn Affan.