From Sahih Bukhari (Hadith 788):
Narrated `Ikrima:I prayed behind a Sheikh at Mecca and he said twenty two Takbirs (during the prayer). I told Ibn `Abbas that he (i.e. that Sheikh) was foolish. Ibn `Abbas admonished me and said, "This is the tradition of Abul-Qasim
Reference: Bukhari 788