Musnad Ahmad 25:1281

Muhammad ibn Ja'far narrated to us, Shu'bah narrated to us, from Qatadah, from 'Ikrimah, who said: I said to Ibn 'Abbas: I prayed the Dhuhr prayer behind a foolish old man, and he said twenty-two takbirs in it; he would say takbir when he prostrated and when he raised his head from prostration. Ibn 'Abbas said: May you have no mother! That is the Sunnah of Abu al-Qasim, may Allah bless him and grant him peace.