Sa’d ibn Abdullah narrated from Ahmad ibn Muhammad, from Musa ibn al-Qasim and Abu Qatadah, from Ali ibn Ja’far, from his brother Imam Musa ibn Ja’far عليه السلام, who said: I asked Imam عليه السلام about a man who performed ablution and forgot to wash his left hand. Imam عليه السلام replied: "He should wash his left hand alone, and he does not need to repeat the ablution for anything else."