Sunan an-Nasa'i 586
سنن النسائي#586SahihIt was narrated that Anas bin Malik said:"If the Messenger of Allah (ﷺ) was setting out on a journey before the sun passed its zenith, he would delay Zuhr until the time of 'Asr, then he would stop and combine the prayer. If the sun passed its zenith before he set out, he would pray Zuhr and then set off
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Abu GhuddahSahih
Al-AlbaniSahih
Zubair Ali ZaiSahih - Agreed Upon
In-book reference: 6:93