Jami` at-Tirmidhi 1531
جامع الترمذي#1531SahihNarrated Ibn 'Umar:That the Messenger of Allah (ﷺ) said: "Whoever swears about an oath and says: 'If Allah wills (Insha Allah), then there is no breaking of the oath against him
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Ahmad Muhammad ShakirSahih
Al-AlbaniSahih
Zubair Ali ZaiIsnaad Sahih
In-book reference: 20:9