Musannaf Ibn Abi Shayba 33:583

Waki’ narrated to us, from ‘Ikrimah ibn ‘Ammar, from Abu ‘Abd Allah al-Filastini, from ‘Abd al-‘Aziz, the brother of Hudhayfah, who said: I heard it from Hudhayfah forty-five years ago. He said: Hudhayfah said: The first thing you will lose of your religion is khushu’ (humility/reverence), and the last thing you will lose of your religion is the prayer.