Musnad Ahmad 1153:21

Ishaq—meaning al-Azraq—and Yahya ibn Sa’id narrated to us. Ishaq said: Husayn ibn al-Maktab narrated to us, from Budayl, from Abu al-Jawza’, from ‘Aishah, who said: "The Messenger of Allah (peace and blessings of Allah be upon him) used to begin the prayer with the takbir (saying 'Allahu Akbar'), and the recitation with 'Al-hamdu lillahi rabbil-'alamin' (Praise be to Allah, Lord of the worlds). When he bowed, he would not raise his head—and Yahya said: he would not lift his head up, nor would he lower it, but [he would keep it] between that—and when he raised his head from bowing, he would not prostrate until he stood upright. And when he raised his head from prostration, he would not prostrate [again] until he sat upright." She said: "He used to say the greeting (tahiyyah) in every two rak'ahs. He used to forbid the 'devil’s sitting' (sitting on the heels). He used to spread out his left foot and keep his right foot upright. He used to forbid that any of us should spread out his forearms like a dog. And he used to conclude the prayer with the taslim (salutation)." Yahya said: "And he used to dislike that one should spread out his forearms like the spreading of a beast of prey."