Sahih al-Bukhari — Call to Prayers (Adhaan) — Hadith No: 803
Translation
Narrated Abu Bakr bin `Abdur Rahman Ibn Harith bin Hisham and Abu Salama bin `Abdur Rahman:Abu Huraira used to say Takbir in all the prayers, compulsory and optional -- in the month of Ramadan or other months. He used to say Takbir on standing for prayer and on bowing; then he would say, "Sami`a l-lahu liman hamidah," and before prostrating he would say "Rabbana wa laka lhamd." Then he would say Takbir on prostrating and on raising his head from the prostration, then another Takbir on prostrating (for the second time), and on raising his head from the prostration. He also would say the Takbir on standing from the second rak`a. He used to do the same in every rak`a till he completed the prayer. On completion of the prayer, he would say, "By Him in Whose Hands my soul is! No doubt my prayer is closer to that of Allah's Messenger (ﷺ) than yours, and this was His prayer till he left this world