Sunan an-Nasa'i 1442
سنن النسائي#1442SahihIt was narrated that Ibn 'Abbas said:"Allah, the Mighty and Sublime, enjoined the prayer on the tongue of your Prophet (ﷺ): While a resident four (rak'ahs), while traveling two, and at times of fear one
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
In-book reference: 15:10