And from him, from al-Hasan, from Fadalah, from Hammad ibn Uthman, from Abu Abdillah عليه السلام, who said:
I asked (Imam عليه السلام): “I reach the night without having performed the ‘witr’, how should I make it up?” Imam عليه السلام said: "Like for like."
Ali Akbar al-Ghaffari
Tahdhīb al-Aḥkām fī Sharḥ al-Muqniʿah, vol. 2, p. 175