Sa’ad from Muhammad ibn al-Husayn from Ali ibn al-Numan from Suwayd al-Qalla from Abu Ayyub from Abu Basir from Abu Abdillah عليه السلام, peace be upon him. He said: I asked Imam al-Sadiq عليه السلام about a man who forgets and prays four rak’ahs while traveling. Imam عليه السلام said: “If he remembers on the same day, then let him repeat (the prayer). But if he does not remember until that day has passed, then there is no repetition upon him.”