Musannaf Ibn Abi Shayba 22:386

Yahya ibn Abi Bukayr narrated to us, he said: Sharik narrated to us, from Abd al-Malik ibn Umayr, from Abd al-Rahman ibn Abd Allah, he said: A man came to Ibn Mas'ud and said: "O Abu Abd al-Rahman, teach me words that are comprehensive and beneficial." He said: "Worship Allah and do not associate anything with Him."