Abdullah bin Saraqah narrates that I heard Sayyiduna Ibn Umar (may Allah be pleased with them) saying: I saw the Messenger of Allah (peace and blessings be upon him) during a journey, and he would not perform (nafl) prayers before or after the obligatory prayer.
Hadith Referenceصحيح ابن خزيمه / جماع أبواب صلاة التطوع فى السفر / 1255