Muhammad ibn Ahmad ibn Yahya from Muhammad ibn Abd al-Hamid from Abu Jamilah from Abu Usamah:
Abu Abdillah عليه السلام was asked about the witr prayer. Imam عليه السلام said: “It is a Sunnah, not an obligation (faridah).”
Ali Akbar al-Ghaffari
Tahdhīb al-Aḥkām fī Sharḥ al-Muqniʿah, vol. 2, p. 260