Musannaf Ibn Abi Shayba 3:2502

'Isa ibn Yunus narrated to us, from al-Awza'i, from al-Mut'im ibn Miqdam, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "A servant does not leave behind for his family anything better than two rak'ahs that he performs with them when he intends to travel."