Yahya related to me from Malik from Muhammad ibn Amr ibn AIqamafrom Malik ibn Abdullah as-Sadi that Abu Hurayra said, "The one whoraises his head and lowers it before the imam - his forelock is in thehand of a shaytan."Malik said, concerning someone who forgotand raised his head before the imam in ruku or sujud, "The sunna ofthat is to return to bowing or prostrating and not to wait for theimam to come up. What he has done is a mistake, because the Messengerof Allah, may Allah bless him and grant him peace, said, 'The imam isappointed to be followed as a leader, so do not oppose him.' AbuHurayra said, 'The one who raises his head and lowers it before theimam - his forelock is in the hand of a shaytan.' "
App reference: Book 3, Hadith 61
USC-MSA web (English) reference: Book 3, Hadith 61
Arabic reference: Book 3, Hadith 208