Musnad Ahmad 1061:2

Yahya ibn Sa'id narrated to us, from 'Abd al-Hamid ibn Ja'far, who said: Muhammad ibn 'Ata' narrated to me, from Abu Humayd al-Sa'idi, who said: I heard him—while he was among ten of the companions of the Prophet, may Allah bless him and grant him peace, one of whom was Abu Qatadah ibn Rib'i—saying: "I am the most knowledgeable among you regarding the prayer of the Messenger of Allah, may Allah bless him and grant him peace." They said to him: "You were not the earliest of us in companionship, nor the most frequent of us in following him." He said: "Yes [I am]." They said: "Then present it." He said: "When he stood for prayer, he stood upright and raised his hands until they were level with his shoulders. When he intended to bow, he raised his hands until they were level with his shoulders, then said: 'Allah is the Greatest,' and bowed. He then remained upright, neither lowering his head nor raising it, and placed his hands on his knees. Then he said: 'Allah hears those who praise Him,' then he rose and stood upright until every bone returned to its place in a balanced manner. Then he fell prostrate and said: 'Allah is the Greatest.' Then he kept his arms away from his sides and opened his upper arms away from his belly, and spread the toes of his feet. Then he bent his left leg and sat upon it, and remained upright until every bone returned to its place. Then he fell prostrate and said: 'Allah is the Greatest.' Then he bent his leg and sat upon it until every limb returned to its place. Then he rose and did the same in the second rak'ah. When he stood up from the two prostrations, he said 'Allah is the Greatest' and raised his hands until they were level with his shoulders, just as he did when he began the prayer. Then he did likewise until, in the rak'ah in which the prayer concludes, he pushed his left leg back and sat on his side in the *tawarruk* position, then he performed the salutation."