´It was narrated that Abu Hurairah said:` "The Messenger of Allah said: 'Whoever swears an oath and says: "If Allah wills, then he has made an exception."'"
Hadith Referenceسنن نسائي / كتاب الأيمان والنذور / 3886
Hadith Gradingالألبانی:صحيح | زبیر علی زئی:إسناده صحيح
Hadith Takhrij«سنن الترمذی/الأیمان 7 (1532)، سنن ابن ماجہ/الکفارات 6 (2104)، (تحفة الأشراف: 13523)، مسند احمد (2/309) (صحیح)»
´Narrated Abu Hurairah:` That the Messenger of Allah (ﷺ) said: "Whoever swears [about an oath] and says: 'If Allah wills (Insha Allah), then he will not have broken it."
Shaykh Dr. Abdur Rahman Freywai
Explanation: 1: That is, he did not break the oath, and for breaking such an oath, there is no expiation (kaffarah) upon him.
Source: Sunan al-Tirmidhi – Majlis ‘Ilmi Dar al-Da‘wah, New Delhi Edition, Page: 1532
´It was narrated from Abu Hurairah that the Messenger of Allah (ﷺ) said:` 'Whoever swears an oath and says In sha' Allah, he will have made an exception."(2)
Maulana Ataullah Sajid
Benefits and Issues: By saying "in sha Allah," an oath is nullified; then, if the action mentioned is not carried out, there is no sin of breaking the oath, nor is expiation (kaffarah) required. The reason for this is that an oath is meant to express a firm resolve, while "in sha Allah" means "if Allah wills, I will do this." And in matters pertaining to the future, a person does not know Allah’s will, so in this, it is as if the resolve is negated, and the possibility arises that perhaps I will be able to do this action, or perhaps I will not.
Source: Commentary on Sunan Ibn Mājah by Mawlānā ‘Atā’ullāh Sājid, Page: 2104