Sunan al-Shafi'i

Abu Nasrah (may Allah have mercy on him) narrates that Sayyiduna Imran bin Husain (may Allah be pleased with him) passed by our gathering, and a young man from the people stood up and asked him about the prayer of the Messenger of Allah (peace and blessings be upon him): how many rak‘ahs did he pray during battles, Hajj, and ‘Umrah? Sayyiduna Imran bin Husain (may Allah be pleased with him) came and stood among us and said, “This young man has asked an important question. I want you all to hear the answer,” or he said something similar. He said: “I performed jihad with the Messenger of Allah (peace and blessings be upon him), and he used to pray two rak‘ahs during battles until we returned to Madinah. I also performed Hajj with the Messenger of Allah (peace and blessings be upon him), and he would pray only two rak‘ahs until we returned to Madinah. I was also present at the conquest of Makkah; the Messenger of Allah (peace and blessings be upon him) stayed in Makkah for eighteen nights, and during that time he prayed only two rak‘ahs. Then he would tell the people of Makkah, ‘You should pray four rak‘ahs in full; we are travelers.’ Sayyiduna Imran (may Allah be pleased with him) says: I performed ‘Umrah and Hajj with Sayyiduna Abu Bakr (may Allah be pleased with him) and also participated in battles with him; Abu Bakr (may Allah be pleased with him) also prayed only two rak‘ahs until we returned to Madinah. I performed several Hajj with Sayyiduna ‘Umar al-Faruq (may Allah be pleased with him); he too prayed only two rak‘ahs until we returned to Madinah. Sayyiduna ‘Uthman (may Allah be pleased with him) performed Hajj for seven years during his caliphate; he also prayed only two rak‘ahs, then in Mina he prayed four rak‘ahs.”