Is an oath nullified if the speaker says 'In sha Allah' (If God wills) following the oath without intervening speech?
General Chapter
Al-Mughni
Book of Oaths
Primary text
If the person swearing says 'In sha Allah' contemporaneously with their oath, this constitutes a valid exception (istithna). Scholars are in agreement that this is termed exception, and whoever makes an exception in their oath does not break it. The basis for this is the Prophet's saying: "Whoever swears an oath and then says, 'In sha Allah,' he has not broken his oath," narrated by Al-Tirmidhi. Another narration by Abu Dawud states: "Whoever swears and makes an exception, he may retract if he wills or may leave it."
Supporting text
Scholars like Malik, Al-Shafi'i, Al-Thawri, Abu Ubayd, and Ishaq consider that the exception must be connected to the oath immediately, such that no extraneous speech separates them, nor should there be a silence during which speech was possible. Silence due to loss of breath, voice, stammering, or an external cause like a sneeze does not invalidate the exception. This ruling is based on the requirement for the exception to immediately follow the oath as it is considered part of the speech, similar to a condition and its answer.