مُسْنَدُ أَحْمَدَ
Musnad Ahmad 1616
Musnad Abu Ishaq Sa'd bin Abi Waqqas
It was narrated from Yahya bin ‘Ubaid al-Bahrani that Muhammad bin Sa"d used to do wudoo’ in az-Zawiyah. One day Muhammad bin Sa"d came out to us from the washroom, and he did wudoo" and wiped over his khuffalo. We were surprised and said: what is this? He said.:My father told me that he saw the Messenger of Allah (ﷺ) do what I have done.
Musnad Ahmad 1617A Hasan hadeeth]