Musannaf Ibn Abi Shayba 3:5260

Sharik narrated to us, from ‘Asim, from Zirr, who said: We used to present the copies of the Qur’an to ‘Abdullah. A man from Thaqif asked him and said: "O Abu ‘Abd al-Rahman, which deeds are best?" He said: "The prayer; and whoever does not pray, there is no religion for him."