It is narrated from Sayyiduna Abu Hurairah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: Whoever swears an oath and says "Insha'Allah" (if Allah wills), then he will not be held accountable for breaking it.
Hadith Referenceالفتح الربانی / كتاب الأيمان والنذور / 5317
Hadith Gradingمحدثین:صحیح
Hadith Takhrij«اسناده صحيح علي شرط الشيخين، أخرجه ابن ماجه: 2104، والترمذي: 1532، (انظر مسند أحمد ترقيم الرسالة: 8088 ترقیم بيت الأفكار الدولية: 8074»
Brief Explanation
Benefits: … It is understood from this that a person who attaches his oath with "in sha Allah" (if Allah wills), he is given the choice to either fulfill that oath or not.