Ali and Uthman performed Hajj together. When we were partway along the road, Uthman forbade tamattu. Ali said, "When you see him set off, set off as well." Then Ali and his companions raised the talbiyah for Umra, and Uthman did not stop them.Ali said, "Was I not informed that you forbid tamattu?"Uthman replied, "Yes."Ali said to him, "Did you not hear that the Messenger of Allah ﷺ performed tamattu?"He answered, "Yes."
أخبرنا عمرو بن علي قال حدثنا يحيى بن سعيد قال حدثنا عبد الرحمن بن حرملة قال سمعت
حج علي وعثمان فلما كنا ببعض الطريق نهى عثمان عن التمتع فقال علي إذا رأيتموه قد ارتحل فارتحلوا فلبى علي وأصحابه بالعمرة فلم ينههم عثمان فقال علي ألم أخبر أنك تنهى عن التمتع قال بلى قال له علي ألم تسمع رسول الله ﷺ تمتع قال بلى
Bukhari narrated it in the book of Hajj, chapter on tamattu, qiran, and ifrad in Hajj, etc., hadith no. 1569, and Muslim in the book of Hajj, chapter on the permissibility of tamattu, hadith no. 1223, from the hadith of Saeed bin Musayab through this route, and it is in Al-Kubra, hadith no. 3713.