We used to eat while walking and drink while standing during the time of the Messenger of Allah ﷺ.
كنا نأكل على عهد رسول الله ﷺ ونحن نمشي، ونشرب ونحن قيام.
Tirmidhi (1880), Ibn Majah (3301), and Ahmad (5874) narrated it, and Ibn Hibban (5322) graded it sahih, all of them through the route of Hafs bin Ghiyath, from Ubaydullah bin Umar, from Nafi, from Ibn Umar, who mentioned it. Tirmidhi said, "This is a sahih hadith, gharib as a hadith of Ubaydullah bin Umar, from Nafi, from Ibn Umar. Imran bin Hudayr narrated this hadith from Abul-Bazri, from Ibn Umar, and Abul-Bazri's name is Yazid bin Attarid." End of quote.I say, the hadith of Abul-Bazri to which Tirmidhi referred was narrated by Ahmad (4601), Ibn Hibban (5243), and Bayhaqi (7/283), all of them through the route of Imran bin Hudayr, from Yazid bin Attarid, from Ibn Umar, who mentioned it. Abul-Bazri, Yazid bin Attarid, had no one narrate from him except Imran bin Hudayr, so he is unknown. However, he is corroborated in the earlier chain by Nafi, except that Bukhari found fault with it, as Tirmidhi mentioned in Ilal al-Kabir (2/791), where he said, "This is a hadith in which there is a problem."I say, Hafs bin Ghiyath is trustworthy, so his being the sole narrator does not cause harm, and this is why the compilers of the Sahih collections included it, and Tirmidhi, Nawawi, and others graded it sahih. Nor is there anything preventing a hadith from having two versions, which is something well known in the transmission of hadith. And Allah knows best.