Sa'd bin 'Ubadah asked the Messenger of Allah (ﷺ) about a vow which his mother had made, but she had died without fulfilling it. The Messenger of Allah (ﷺ) said: "Fulfill it on her behalf ."

"Whoever swears an oath and says In sha' Allah, will never break his oath."

the Messenger of Allah (ﷺ), said: "Whoever swears an oath then sees that something else is better than it, let him do that which is better and offer expiation for what he swore about. "

"The Messenger of Allah (ﷺ) offered expiation of a Sa' of dates, and he enjoined the people to do likewise. Whoever does not have that (must give) half a Sa' of wheat."

"A man would give his family food that was abundant and another would give his family food that was barely sufficient, then the following was revealed: 'With the Awsat of that with which you feed your families...’”(2)

'The Messenger of Allah (ﷺ) commanded us to help fulfill the oath."

"We went out looking for the Messenger of Allah (ﷺ) and Wa'il bin Hujr was with us. An enemy of his seized him and the people were reluctant to swear an oath but I swore that he was my brother, so they set him free. We came to the Messenger of Allah (ﷺ) and I told him that the people had been reluctant to swear an oath, but I had sworn that he was my brother. He said: 'You told the truth. The Muslim is the brother of his fellow Muslim.' "

"[There is no vow to commit disobedience and] no vow concerning that which the son of Adam does not possess."

"There is no vow to commit disobedience, and the expiation (for such a vow) is the expiation for breaking an oath."

"Whoever makes a vow and does not state it specifically, the expiation (for such a vow) is the expiation for breaking an oath. Whoever makes a vow and is not able to fulfill it, the expiation for that is the expiation for breaking an oath. Whoever makes a vow and is able to fulfill it, let him do so."

"I made a vow during the Ignorance period and I asked the Prophet (ﷺ) (about it) after I became Muslim. He told me to fulfill my vow."

"The swearing of the Messenger of Allah (ﷺ) when he took an oath and I bear witness before Allah was: 'By the One in Whose Hand is my soul."'

the Messenger of Allah (ﷺ) said: 'Do not take oaths by idols nor by your forefathers. "

"I took an oath by Lat and 'Uzza. The Messenger of Allah (ﷺ) said : 'Say: "La ilaha illallah wahdahu la sharika lahu" (None has the right to be worshipped but Allah alone, with no partner or associate)," then spit toward your left three times, and seek refuge with Allah, and do not do that again."'

The Messenger of Allah (ﷺ) said: 'Whoever takes an oath to follow a religion other than Islam, telling a deliberate lie, he will be as he said.'"

"If that happens, I will be a Jew." The Messenger of Allah (ﷺ) said: 'That is guaranteed."

the Messenger of Allah (ﷺ) said: "Whoever says: 'I have nothing to do with Islam,' if he is lying then he is as he said, and if he is telling the truth, his Islam will not be sound."

"The Messenger of Allah (ﷺ) heard a man taking an oath by his father and said: 'Do not make oaths by your forefathers. Whoever makes an oath by Allah, let him fulfill his oath, and if an oath is sworn for a person by Allah, let him accept it. Whoever is not content with Allah has nothing to do with Allah.'

the Messenger of Allah (ﷺ) said: "An oath (leads to) either sin or regret. "

'Whoever swears an oath and says In sha' Allah, he will have made an exception."(2)