The Book of Purification
1/67. Chapter:
How Many Times Should (Parts Of The Body) Be Washed?
Sunan an-Nasai
أَخْبَرَنَا حُمَيْدُ بْنُ مَسْعَدَةَ، عَنْ سُفْيَانَ، - وَهُوَ ابْنُ حَبِيبٍ - عَنْ شُعْبَةَ، عَنِ النُّعْمَانِ بْنِ سَالِمٍ، عَنِ ابْنِ أَبِي أَوْسٍ، عَنْ جَدِّهِ، قَالَ رَأَيْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم اسْتَوْكَفَ ثَلاَثًا .
It was narrated from (Aws bin) Abi Aws that his grandfather said: "I saw the Messenger of Allah (ﷺ) trickle water into his hand until it started to drip from his hand, three times."
Reference : Sunan an-Nasa'i 83In-book reference : Book 1, Hadith 83English translation : Vol. 1, Book 1, Hadith 83