كتاب الطهارة
1  
The Book of Purification
(4)
Chapter: Ablution (Wudu)
(4)
باب الوضوء
Bulugh al-Maram 35
In another narration by al-Bukhari and Muslim:
"He started with the front of his head, moved them (his hands) to the nape of his neck, and then returned them to the place where he started."
وَفِي لَفْظٍ: { بَدَأَ بِمُقَدَّمِ رَأْسِهِ, حَتَّى ذَهَبَ بِهِمَا إِلَى قَفَاهُ, ثُمَّ رَدَّهُمَا إِلَى اَلْمَكَانِ اَلَّذِي بَدَأَ مِنْهُ } 1‏ .‏


‏1 ‏- البخاري (185)‏، ومسلم (235)‏.‏

Reference : Bulugh al-Maram 35
In-book reference : Book 1, Hadith 41
English translation : Book 1, Hadith 40