Sunan an-Nasa'i 5530
سنن النسائي#5530SahihIt was narrated that Ibn 'Umar said:"The Prophet [SAW] used to say: 'Allahumma (O Allah,)' and he mentioned the supplication, and said at the end, 'A'udhu bika an ughtala min tahti (and I seek refuge with You from being swallowed up from beneath me)
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 ZaiHasan
In-book reference: 50:103