Musnad Ahmad 28:362

Muhammad ibn Ja‘far and Hashim ibn al-Qasim narrated to us, they said: Shu‘bah narrated to us, from ‘Amr ibn Murrah, from Ibrahim, from Masruq, who said: They mentioned Ibn Mas‘ud in the presence of ‘Abdullah ibn ‘Amr, and he said: "That is a man whom I will never cease to love, after I heard the Messenger of Allah, peace and blessings of Allah be upon him, say: 'Seek the recitation of the Qur’an from four: from Ibn Mas‘ud, Salim the freed slave of Abu Hudhayfah, Ubayy ibn Ka‘b, and Mu‘adh ibn Jabal.'"