Sunan an-Nasa'i 3832
سنن النسائي#3832SahihIt was narrated from 'Uqbah bin 'Amir that the Messenger of Allah said:"The expiation for vows is the expiation for an oath
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 ZaiIsnaad Sahih
In-book reference: 35:72