Sunan Abi Dawud 3261
سنن أبي داود#3261SahihNarrated Abdullah ibn Umar: The Prophet (ﷺ) said: If anyone says when swearing an oath: "If Allah wills," he makes an exception
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniSahih
Muhammad Muhyi Al-Din Abdul HamidSahih
Shuaib Al ArnautSahih
Zubair Ali ZaiSahih
In-book reference: 22:20