Hazrat Hafs says that we went out with Hazrat Ibn Umar (may Allah be pleased with them). We performed the obligatory prayer, and he saw one of his children performing a voluntary (nafl) prayer. He said: I have prayed with the Messenger of Allah (peace and blessings be upon him), Hazrat Abu Bakr, Hazrat Umar, and Hazrat Uthman, and during travel, they would not perform any prayer before or after the obligatory prayers. If I were to perform a voluntary prayer, I would perform it completely.