It wasnarrated from Maimunah that when the Prophet (ﷺ) prostrated,hewould hold his forearms away from his sides, such that if a lambwanted to pass under his arms, it would be able to do so. (FR)
English reference (FR): Vol. 1, Book 5, Hadith 880 (FR)
Arabic reference (FR): Book 5, Hadith 929 (FR)