Musnad Ahmad 549
It was narrated that Qatadah said:
Az-Zubair offered the funeral prayer for `Uthman (رضي الله عنه) and buried him in accordance with his instructions.
حَدَّثَنَا عَبْدُ الرَّزَّاقِ، حَدَّثَنَا مَعْمَرٌ، عَنْ قَتَادَةَ، قَالَ صَلَّى الزُّبَيْرُ عَلَى عُثْمَانَ رَضِيَ اللَّهُ عَنْهُ وَدَفَنَهُ وَكَانَ أَوْصَى إِلَيْهِ‏.‏