When the Prophet ﷺ prostrated he would hold his arms out from his sides so that if a lamb wanted to pass beneath his arms it would be able to do so.  

أَنَّ النَّبِيَّ ﷺ كَانَ إِذَا سَجَدَ جَافَى يَدَيْهِ حَتَّى لَوْ أَنَّ بَهْمَةً أَرَادَتْ أَنْ تَمُرَّ تَحْتَ يَدَيْهِ مَرَّتْ