Musannaf Ibn Abi Shayba 3:4475

Yazid ibn Harun narrated to us, he said: Yahya ibn Sa'id informed us that Muhammad ibn Yahya ibn Habban informed him that Ibn Muhayriz al-Qurashi informed him, from al-Mukhaddaji, a man from Banu Kinana, that he informed him that a man from the Ansar who was in al-Sham, whose kunya was Abu Muhammad and who had companionship [with the Prophet], used to say: "The Witr prayer is obligatory." Al-Mukhaddaji mentioned that he went to 'Ubadah ibn al-Samit and mentioned that to him. So 'Ubadah said: "Abu Muhammad lied. I heard the Messenger of Allah (peace and blessings of Allah be upon him) say: 'Five prayers which Allah has prescribed upon the servants. Whoever comes with them, not neglecting anything of their rights, comes having a covenant with Allah that He will enter him into Paradise. And whoever diminishes anything of their rights, comes having no covenant with Allah; if He wills, He will punish him, and if He wills, He will enter him into Paradise.'"