Musnad Ahmad 551
It was narrated that Abul `Aliyah said:
We were guarding the door of `Uthman (رضي الله عنه) for the first ten days of [Dhul-Hijjah].
حَدَّثَنَا أَبُو نُعَيْمٍ، حَدَّثَنَا أَبُو خَلْدَةَ، عَنْ أَبِي الْعَالِيَةِ، قَالَ كُنَّا بِبَابِ عُثْمَانَ رَضِيَ اللَّهُ عَنْهُ فِي عَشْرِ الْأَضْحَى‏.‏