Sunan an-Nasa'i 594
سنن النسائي#594SahihIt was narrated from Anas that the Messenger of Allah (ﷺ) said:"If the Messenger of Allah (ﷺ) wanted to travel quickly, he would delay Zuhr until the time of 'Asr and combine them, and he would delay Maghrib until he combined it with 'Isha' when the twilight had disappeared
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 Muslim
In-book reference: 6:101