Musnad Ahmad 424
It was narrated that Sa`eed bin al-Musayyab said,  `Uthman went for Hajj, and when he was halfway there, `Ali was informed that `Uthman had told his companions not to do tamattu`, `Ali said to his companions:
When he sets out, set out too. `Ali and his companions entered ihram for ‘Umrah, and `Uthman did not say anything to them. `Ali said: Have I not been told that you have forbidden tamattu.” Didn`t the Messenger of Allah (ﷺ) do tamattu`? He (the narrator) said: I do not know what answer `Uthman (رضي الله عنه) gave.
حَدَّثَنَا عَبْد اللَّهِ، حَدَّثَنَا مُحَمَّدُ بْنُ أَبِي بَكْرٍ الْمُقَدَّمِيُّ، حَدَّثَنِي أَبُو مَعْشَرٍ يَعْنِي الْبَرَّاءَ، وَاسْمُهُ، يُوسُفُ بْنُ يَزِيدَ حَدَّثَنَا ابْنُ حَرْمَلَةَ، عَنْ سَعِيدِ بْنِ الْمُسَيَّبِ، قَالَ حَجَّ عُثْمَانُ حَتَّى إِذَا كَانَ فِي بَعْضِ الطَّرِيقِ أُخْبِرَ عَلِيٌّ أَنَّ عُثْمَانَ نَهَى أَصْحَابَهُ عَنْ التَّمَتُّعِ بِالْعُمْرَةِ وَالْحَجِّ فَقَالَ عَلِيٌّ لِأَصْحَابِهِ إِذَا رَاحَ فَرُوحُوا فَأَهَلَّ عَلِيٌّ وَأَصْحَابُهُ بِعُمْرَةٍ فَلَمْ يُكَلِّمْهُمْ عُثْمَانُ فَقَالَ عَلِيٌّ رَضِيَ اللَّهُ عَنْهُ أَلَمْ أُخْبَرْ أَنَّكَ نَهَيْتَ عَنْ التَّمَتُّعِ أَلَمْ يَتَمَتَّعْ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ فَمَا أَدْرِي مَا أَجَابَهُ عُثْمَانُ رَضِيَ اللَّهُ عَنْهُ‏.‏