61. Virtues and Merits of the Prophet (pbuh) and his Companions - كتاب المناقب
23) Chapter: The description of the Prophet (saws)
Narrated `Abdullah bin Malik bin Buhaina Al-Asdi:
When the Prophet (ﷺ) prostrated, he used to keep his arms so widely apart that we used to see his armpits.
(The sub-narrator, Ibn Bukair said, "The whiteness of his armpits.")
