The closest of people to the Prophet (peace and blessings be upon him) in conduct and manner was Ibn Mas'ud (may Allah be pleased with him)

Shaqiq relates: I heard Sayyiduna Hudhayfah (may Allah be pleased with him) say: "In his habits and manners, his bearing and his ways, Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) was the most similar of people to the Messenger of Allah (peace and blessings be upon him), from the time he left his house until he returned (he was an embodied model of the Sunnah). I do not know what his affairs inside his house were like. However, the well-informed Companions of the Messenger of Allah (peace and blessings be upon him) know that Ibn Umm Abd (Abdullah bin Mas'ud) will be among the closest to Allah on the Day of Resurrection."
This hadith is sahih (authentic) on the condition of the two Shaykhs (Bukhari and Muslim), but they did not record it.

Awn bin Abdullah bin Utbah narrates from his father that the state of worship of Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) was such that when all eyes had gone to sleep, a sound like the humming of bees (of recitation and weeping) would be heard from him until the morning.