Jami at Tirmidhi 278

Al-Bara bin Azib narrated: The Salat of Allah's Messenger (was such that) when he bowed, and when he raised his head from bowing, and when he prostrated, and when he raised his head from prostration it (all) was nearly the same. ..

Al-Bara bin Azib narrated: (Another chain) which is similar. ..

Al-Bara said: When we performed Salat behind Allah's Messenger, he would raise his head from bowing, and no man among us would bend his back until Allah's Messenger prostrated, then we prostrated. ..

Ali narrated: Allah's Messenger said to me: 'O Ali! I love for you what I love for myself, and I dislike for you what I dislike for myself. Do not squat between prostrations.' ..

Tawus said: We asked Ibn Abbas about squatting (sitting) on the heels. He said: 'It is the Sunnah.' We said: 'We think that it is difficult for a man.' He said: 'Rather, it is Sunnah of your Prophet.' ..

Ibn Abbas narrated: Between the two prostrations, the Prophet would say: (Allahummaghfir li, warhamni, wajburni, wahdini, warzuqni). 'O Allah! Pardon me, have mercy on me, help me, guide me, and grant me sustenance.' ..