From him from Muhammad ibn Abi Umayr from Hisham ibn Salim from Muhammad ibn Muslim who said: I entered upon Abu Ja'far, peace be upon him, while He عليه السلام was in prayer. I said: "Peace be upon you," And Imam عليه السلام replied: "Peace be upon you." I asked: "How did you wake up?" But Imam عليه السلام remained silent, and when He عليه السلام finished, I said to Imam عليه السلام: "Does one return the salam while in prayer?" Imam عليه السلام said: "Yes, in the manner it was said to him."