Ali ibn Mahziyar from Fadalah and Hammad ibn Isa from Mu'awiyah ibn Wahb who said:
I asked Abu Abdillah عليه السلام, peace be upon him, about the best time for the witr prayer. Imam عليه السلام said: "The beginning of dawn is the best for that."
Ali Akbar al-Ghaffari
Tahdhīb al-Aḥkām fī Sharḥ al-Muqniʿah, vol. 2, p. 361