Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) narrates this saying of the Prophet (peace and blessings be upon him): "The witr is wajib (obligatory) upon every Muslim."
Imam al-Bazzar recorded this narration; its chain contains a narrator, Jabir al-Ju'fi, about whom much has been said, though Sufyan al-Thawri declared him thiqah (trustworthy).