Musannaf Ibn Abi Shayba 3:5780

Abu al-Ahwas narrated to us, from Abu Ishaq, from Abu Sa'id, from Shafi, who said: I said to Ibn Abbas, "We are a people who, when we travel, have with us those of our servants who suffice us in service, so how should we pray?" He said, "When the Messenger of Allah (ﷺ) traveled, he would pray two rak'ahs until he returned." He said: Then I returned and asked him, and he said the same thing. Then I returned again, and some of the people said to me, "Do you not understand? Do you not hear what he is saying to you?"