Maymuna bint Harith reported,

She said, "When the Prophet ﷺ prostrated, if a young lamb had wished to pass in front of him, it could have passed through."In another narration, "When the Messenger of Allah ﷺ prostrated, he would spread his arms out wide, meaning he held them away from his sides, until the whiteness of his armpits could be seen from behind him, and when he sat, he would settle comfortably on his left thigh."In another narration, "When he prostrated, he held his arms away from his sides until the whiteness of his armpits could be seen from behind him."

عن ميمونة بنت الحارث زوج النبي ﷺ

قالت: كان النبي ﷺ إذا سجد، لو شاءت بهمة أن تمر بين يديه لمرت. وفي رواية: كان رسول الله ﷺ إذا سجد خوى بيديه ( يعني جنح) حتى يرى وضح إبطيه من ورائه، وإذا قعد اطمأن على فخذه اليسرى. وفي رواية: إذا سجد جافي حتى يرى من خلفه وضح إبطيه.