(4) باب الوضوء
Narrated 'Ali (rad) regarding the description of the ablution of the Prophet (ﷺ):
He (the Prophet) wiped his head (with water) only once. [Reported by Abu Da'ud, An-Nasa'i, AtTirmidhi with a Sahih Sanad (authentic chain of narrators). At-Tirmidhi said, "It's the most Hadith on this subject"].
Reference: Bulugh al-Maram 34
In-book reference: Book 1, Hadith 39
English translation: Book 1, Hadith 38