Sahih Muslim Book - 15, Hadith - 2964

وَحَدَّثَنَا مُحَمَّدُ بْنُ الْمُثَنَّى وَمُحَمَّدُ بْنُ بَشَّارٍ قَالاَ حَدَّثَنَا مُحَمَّدُ بْنُ جَعْفَرٍ حَدَّثَنَا شُعْبَةُ عَنْ عَمْرِو بْنِ مُرَّةَ عَنْ سَعِيدِ بْنِ الْمُسَيَّبِ قَالَ اجْتَمَعَ عَلِىٌّ وَعُثْمَانُ - رضى الله عنهما - بِعُسْفَانَ فَكَانَ عُثْمَانُ يَنْهَى عَنِ الْمُتْعَةِ أَوِ الْعُمْرَةِ فَقَالَ عَلِىٌّ مَا تُرِيدُ إِلَى أَمْرٍ فَعَلَهُ رَسُولُ اللَّهِ -صلى الله عليه وسلم- تَنْهَى عَنْهُ فَقَالَ عُثْمَانُ دَعْنَا مِنْكَ. فَقَالَ إِنِّى لاَ أَسْتَطِيعُ أَنْ أَدَعَكَ فَلَمَّا أَنْ رَأَى عَلِىٌّ ذَلِكَ أَهَلَّ بِهِمَا جَمِيعًا.

It was narrated that Saeed bin Al-Musayyab said: “Ali and Uthman [may Allah be pleased with them] met in Usfan, and Uthman used to forbid Tamattu and Umrah (during the Hajj season). Ali said: ‘what do you mean by forbidding something that the Messenger of Allah (SAW) did?’ Uthman said: ‘Leave us alone.’ He said: ‘I cannot leave you alone.’ When Ali saw that, he entered Ihram for both of them together. ”