Sa'id bin Shufay al-Hamdani (may Allah have mercy on him) narrated: I asked Sayyiduna Ibn Abbas (may Allah be pleased with them both) about the prayer while travelling, and he said: When the Messenger of Allah (peace and blessings be upon him) left his family on a journey, he would pray two rak'ahs until he returned to his family.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 12658