We were on a journey, and Ibn Umar was with us. I asked him about voluntary prayers, and he replied, "I saw the Messenger of Allah ﷺ not perform any voluntary prayers during travel, neither before the obligatory prayer nor after it."
كنا في سفر، ومعنا فسألته فقال: رأيت رسول الله ﷺ لا يسبح في الصلاة في السفر قبل الصلاة ولا بعدها.
Imam Ahmad narrated it (5012) from Yazid bin Harun, who said, Ibn Abu Dhib informed us, from Uthman bin Abdullah bin Suraqa, and he related the hadith. Its chain is sahih. What is meant here by "glorification" (tasbih) is the regular sunnah prayer, otherwise it is indeed established from him that he used to perform the glorification (voluntary prayer) on the back of his mount wherever it faced. Shafii said, It is established from the Prophet ﷺ that he used to perform voluntary night prayers while shortening the obligatory prayers. Ahmad was asked about voluntary prayer while traveling, and he said, I hope there is no harm in voluntary prayer while traveling.As for what was reported from Bara bin Azib Ansari, who said, "I accompanied the Messenger of Allah ﷺ on eighteen journeys, and I never saw him omit the two rakahs when the sun had passed its zenith before Dhuhr," this is a daif hadith. Abu Dawud narrated it (1222), and Tirmidhi (550), both from the hadith of Layth bin Saad, from Safwan bin Salim, from Abu Busra Ghifari, from Bara bin Azib, who related it.Tirmidhi said, This is a gharib hadith. He said, I asked Muhammad, meaning Bukhari, about it, and he did not recognize it except through the hadith of Layth bin Saad, and he did not know the name of Abu Busra, though he considered it hasan.I say, Abu Busra, with the ba pronounced with a "u" sound and the sin unvowelled, is unknown, as Dhahabi said. No one deemed him reliable except Ibn Hibban, so he is majhul (unknown).