Abu Muhammad claimed that the witr prayer is obligatory. Ubada bin Samit said, "Abu Muhammad has spoken falsely. I bear witness that I heard the Messenger of Allah ﷺ say, 'There are five prayers which Allah the Exalted has made obligatory. Whoever performs their ablution well, prays them at their proper times, and completes their bowing and humility, has a covenant with Allah that He will forgive him. Whoever does not do so has no covenant with Allah. If He wishes, He may forgive him, and if He wishes, He may punish him.'"
حدثنا محمد بن حرب الواسطي حدثنا يزيد يعني ابن هارون حدثنا محمد بن مطرف عن زيد بن أسلم عن عطاء بن يسار
زعم أبو محمد أن الوتر واجب فقال عبادة بن الصامت كذب أبو محمد أشهد أني سمعت رسول الله ﷺ يقول خمس صلوات افترضهن الله تعالى من أحسن وضوءهن وصلاهن لوقتهن وأتم ركوعهن وخشوعهن كان له على الله عهد أن يغفر له ومن لم يفعل فليس له على الله عهد إن شاء غفر له وإن شاء عذبه
[Its isnad is sahih]. Ahmad narrated it, 5/317, from the hadith of Muhammad bin Mutarrif, through the same chain.It occurs in the manuscript copies of Abu Dawud as "Abdullah bin Sanabihi," which is an error. The correct form is "Abu Abdullah Sanabihi," who is Abdul-Rahman bin Usaylah.