Musannaf Ibn Abi Shaybah 2666 — Keeping the limbs apart in prostration

Ubaydullah bin Abdullah bin Aqram al-Khuza'i narrates from his father (may Allah be pleased with him), who said: I was with my father at Namirah when some riders passed by us and made camp at one side of the road. My father said to me: "My dear son, stay with these animals of yours; I will be back shortly." When he set off, I went along with him, and there was the Messenger of Allah (peace and blessings be upon him). He prayed, and I prayed with him, and during the prayer I was looking at the whiteness of the armpits of the Messenger of Allah (peace and blessings be upon him).