Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) narrates: The Prophet (peace and blessings be upon him) said: "The witr is binding upon the people of the Qur'an."
Imam al-Tabarani recorded this narration in al-Mu'jam al-Saghir; its chain contains a narrator, Imran al-Khayyat, about whom Imam al-Dhahabi says: He is not known.