Musnad Ahmad 1034:102

Mu'awiyah narrated to us, Za'idah narrated to us, from al-A'mash, from Shaqiq, who said: I was sitting with Hudhayfah when Abdullah ibn Mas'ud approached. Hudhayfah said: "Indeed, the person most similar in conduct and manner to the Messenger of Allah, may Allah bless him and grant him peace, from the time he leaves his house until he returns—though I do not know what he does with his family—is Abdullah ibn Mas'ud." By Allah, the preserved ones among the companions of Muhammad, may Allah bless him and grant him peace, certainly knew that Abdullah was among those closest to Allah in means on the Day of Resurrection.