Sahih Muslim
The Book Pertaining to the Merits of the Companions (Allah Be Pleased With Them) of the Holy Prophet (May Peace Be Upon Him) (Kitab Al-Fadail Al-Sahabah)
Book Number: 031 / Hadith Number: 6017
Abu Musa reported: When I and my brother came from Yemen we used to consider Ibn Mas'ud and his mother amongst the members of the household. of Allah's Messenger (may peace be upon him) because of their visiting them frequently and staying there for long (periods of) time.