Those who take an oath not to have sexual relation with their wives must wait four months, then if they return (change their idea in this period), verily, Allah is Oft-Forgiving, Most Merciful.

He [Ya'qub (Jacob)] said: "I will not send him with you until you swear a solemn oath to me in Allah's Name, that you will bring him back to me unless you are yourselves surrounded (by enemies, etc.)," And when they had sworn their solemn oath, he said: "Allah is the Witness over what we have said."

And they swore by Allah their most binding oath, that if a warner came to them, they would be more guided than any of the nations (before them), yet when a warner (Muhammad ﷺ) came to them, it increased in them nothing but flight (from the truth),

"And take in your hand a bundle of thin grass and strike therewith (your wife), and break not your oath. Truly! We found him patient. How excellent (a) slave! Verily, he was ever oft-returning in repentance (to Us)!

And verily, that is indeed a great oath, if you but know.