Musannaf Ibn Abi Shaybah 2663 — Keeping the limbs apart in prostration

Salim al-Barrad said: We came to visit Sayyiduna Abu Mas'ud (may Allah be pleased with him) in his room, and we said to him: "Teach us the manner of prayer of the Messenger of Allah (peace and blessings be upon him)." So he prayed, and when he prostrated, he kept his elbows spread apart.