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)‏.‏