Sahih Bukhari
Characteristics of Prayer
Volume: 001 / Book Number: 012 / Hadith Number: 754
Narrated 'Ikrima:
I saw a person praying at Muqam-lbrahim (the place of Abraham by the Ka'ba) and he was saying Takbir on every bowing, rising, standing and sitting. I asked Ibn 'Abbas (about this prayer). He admonished me saying: "Isn't that the prayer of the Prophet?"