Sunan Abi Dawud Book 2, Hadith 345
When he (the Prophet) prostrated he kept his thighs wide and did not let his belly touch the thighs.
Abu Dawud says that Ibn Mubarak narrated this hadith from ‘Abbas b. Sahl, which he did not remember well. It is thought that he has mentioned ‘Isa b. ‘Abd Allah, ‘Abbas b. Sahl and Abu Humaid al-Sa’idi.
Abu Humaid, Abu Usaid, Sahl. B Sa’d and Muhammad b. Maslamah (once) got together and discussed how the Messenger of Allah(ﷺ) used to offer his prayer. Abu Humaid said: I am more informed than any of you regarding the prayer offered by the Messenger of Allah (ﷺ). Then he mentioned a part of it, and said: He then bowed and placed his hands upon his knees as if he caught hold of them; and bent them, keeping (his arms) away from his sides. He them prostrated himself and placed his nose and forehead (on the ground); and kept his arms away from his side, and placed his palms (on the ground opposite his shoulders; he then raised his head that every bone returned to its proper place; (he then prostrated twice) until he finished this prostrations). Then he sat down and spread out his left foot, putting forward the front of his right foot towards the qiblah placing the palm of his right hand on his right knee, and the palm of his left hand on his left knee, and he pointed with his finger.
Abu Dawud said: This tradition has been narrated by Ibn al-Mubarak from Fulaih who heard ‘Abbas . Sahl narrating it; but I do not remember it. I think he made the mention of ‘Isa b. ‘Abd Allah who heard ‘Abbas b. Sahl saying: I accompanied Abu Humaid al-Sa’idi.
When he prostrated, his knees touched the ground before his palms touched it; when he prostrated himself, he placed his forehead on the ground between his palms, and kept his armpits away from his sides.
Hajjaj reported from Hammam and Shaqiq narrated a similar tradition to us from ‘Asim b. Kulaib on the authority of his father from the Prophet(ﷺ).
And another version narrated by one of them has-and I think in all probability that this version has been narrated by Muhammad b. Juhadah-when he got up (after prostration), he got up with his knees and gave his weight on his thighs.