(Imām Bukhārī narrates): Yahyā ibn Bukair narrated to us, he said: Bakr ibn Mudar narrated to us, from Ja'far, from Ibn Hurmuz, from 'Abdullāh ibn Mālik ibn Buhainah, that:

the Prophet ﷺ, when he prayed, kept his arms spread wide, until the whiteness of his armpits was visible.

And Laith said: Ja'far ibn Rabī'ah narrated to me similar to this hadith.