It is narrated from Muhammad bin Amr bin Ata that he said: I was in a gathering of the Companions of the Messenger of Allah (peace and blessings be upon him) (may Allah be pleased with them). They began to talk about the prayer of the Messenger of Allah (peace and blessings be upon him). Abu Humayd al-Sa'idi (may Allah be pleased with him) said: "I know more about the prayer of the Messenger of Allah (peace and blessings be upon him) than all of you. I saw the Messenger of Allah (peace and blessings be upon him): when he (peace and blessings be upon him) stood for prayer he would say the takbir, then recite. When he bowed he would also say the takbir, and while bowing he would place his hands on his knees and keep his fingers spread apart, and he would neither lower his back too much nor raise it, but keep it level. When he rose from bowing he would stand straight until every limb returned to its place. Then, when he prostrated, he would place his palms, his knees and the tips of his feet firmly on the ground and prostrate with composure. When he raised his head he would sit up straight with composure. After two rak'ahs he would sit, and his way was to keep the right foot upright and lay the left foot flat and sit on it. When it was the fourth rak'ah he would sit on his left hip and bring both feet out to one side."
The Shaykh (may Allah have mercy on him) says: In the narration of Abbas bin Sahl from Abu Humayd (may Allah be pleased with him) it is that "In prostration he (peace and blessings be upon him) would support himself on his palms, his knees and the tips of his feet."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2643