Abbas bin Sahl (may Allah have mercy on him) says that Abu Humayd, Abu Usayd, Sahl bin Sa'd and Muhammad bin Maslamah (may Allah be pleased with them) were sitting together. They began discussing the prayer of the Messenger of Allah (peace and blessings be upon him). Abu Humayd (may Allah be pleased with him) said: "I am the most knowledgeable of you all about the prayer of the Messenger of Allah (peace and blessings be upon him)." Then he mentioned the complete hadith. In it there is that he (peace and blessings be upon him) prostrated, firmly placing his nose and forehead on the ground, keeping his arms away from his sides, and placing his palms level with his shoulders.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2694