Taking an oath in the belief that something is true

A 1: If the case is as you have mentioned that the man swore, on his wife becoming forbidden to him, that he truly gave his friend fifty Riyals of the money he owed, this does not lead to breaching his oath, even if he later discovers that he was mistaken. Allah (Exalted be He) said, And there is no sin on you concerning that in which you made a mistake, except in regard to what your hearts deliberately intend. The Prophet (peace be upon him) said, Allah has pardoned for me my Ummah for [their] mistakes and [their] forgetfulness and for what they have done under duress. Also, the man did not (Part No. 23; Page No. 61) have the intention to do so, and hence he did not break his oath. This is the opinion of many scholars and the preponderant view in Al-Shafi`y's Madh-hab (school of Jurisprudence) as mentioned in Al-Khulasah. It is said in Al-Furu`: This is the preponderant opinion. It is said also in Al-Insaf: It is the soundest opinion, which was chosen by Shaykh-ul-Islam Taqy Al-Din Ibn Taymiyyah. Q 2: A dispute arose between a man and his cousin over an accident caused by the latter in a common threshing floor, and the man swore "by the prohibition" on removing the remains of the accident. Later, reconciliation was made to keep the remains in their place. What does the man incur as a result of this oath? A: If the case is as you have mentioned that the man swore by the prohibition on removing the remains of the accident, then they agreed to keep the remains in their place, he broke his oath and has to pay a Kaffarah (expiation) for breaking it. The Kaffarah is feeding or clothing ten Miskins (needy) or freeing a believing slave. If he can not afford any of these alternatives, he has to observe fasting for three days, preferably in a consecutive manner. As the man did not specify that his wife would be forbidden to him, and only swore by the prohibition on removing the remains of the accident, the prohibition would not affect his marital relation with his wife.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.