Usama bin Zaid says: I asked Tawus about offering voluntary prayers during travel, while Hasan bin Muslim was also sitting there. Hasan bin Muslim said, and Tawus was listening, that Tawus narrated to us from Sayyiduna Abdullah bin Abbas (may Allah be pleased with him), who said that the Messenger of Allah (peace and blessings be upon him) made the prayers obligatory in both residence and travel. Therefore, just as you offer (voluntary) prayers before and after the obligatory prayer while residing, in the same way, you should also offer the preceding and following (Sunnah) prayers during travel.