Al-Husayn ibn Sa‘id from Faddalah and Safwan from al-‘Ala’ from Muhammad ibn Muslim from one of the two (Imams عليه السلام), peace be upon them, who said:
I asked Imam عليه السلام about forgetfulness in the supererogatory prayer. Imam عليه السلام said: "There is nothing upon you."
Ali Akbar al-Ghaffari
Tahdhīb al-Aḥkām fī Sharḥ al-Muqniʿah, vol. 2, p. 369