It wasnarrated that Ibn 'Abbas said:
"It was said: 'O Messenger ofAllah, why did you support (by supplicating for) those who shave(their heads) three times and those who cut (their hair) only once?'He said: 'Because they did not entertain any doubts.'" (TR)
English reference (TR): Vol. 4, Book 25, Hadith 3045 (TR)
Arabic reference (TR): Book 25, Hadith 3161 (TR)