When the Prophet ﷺ prostrated, he would hold his arms away from his sides so much that if a young lamb wanted to pass beneath his arms, it could have done so.
أخبرنا قتيبة قال حدثنا سفيان عن عبيد الله وهو ابن عبد الله بن الأصم عن عمه يزيد وهو ابن الأصم
أن النبي ﷺ كان إذا سجد جافى يديه حتى لو أن بهمة أرادت أن تمر تحت يديه مرت
Muslim narrated it, in the Book of Prayer, chapter on moderation in sujud and placing the palms on the ground, etc., hadith no. 496, from the hadith of Sufyan bin Uyayna, with this chain, and it is also found in Kubra, hadith no. 697.Abu Dawud narrated it, in the Book of Prayer, chapter on the description of sujud, hadith no. 898, from Qutayba, with this chain.