In verse 4:20 of the Holy Quran Allah (swt) strictly condemns the married men who contemplate divorcing their wife, from taking back the dower/meher from their wife. Even if they had offered their wife a fortune at the time of the marriage, yet it will be considered to be a grave sin on their part, to take it back.
In the next verse, i.e. 4:21 Allah (swt) explains why it is a sin on the part of the men to take back the dowers by reminding them about the physical proximity that they had shared with their wife. Allah (swt) also reminds them about the solemn covenant or the strong pledge that their wife has taken from them at the time of their marriage, according to which the wife should be retained honorably or set free with full respect.
In verse 2:222 Allah (swt) says to Prophet Mohammad (saw) that when the people ask you about menstruation you tell them that it is filth and the men should avoid sexual intercourse with their wives during their menstruation period. Once their menstrual cycle gets over and the women become hygienic (after taking a bath), their husband can have sexual intercourse with then in a way as Allah (swt) has told them. Allah (swt) likes those who seek His forgiveness and who are clean and pure. The background of this verse is that during the pre-Islamic days, the Jews used to mistreat their wives during their menstruation period. They were treated like untouchables or outcastes. The Jews did not like to mingle with their wives at all during this time. In fact, they even used to stop eating and drinking with them. The Sahabas (ra) asked Prophet Mohammad (saw) regarding this custom. It was in this context that the verse 2:222 was revealed by Allah (swt) in which only sexual intercourse is prohibited with one’s wife during her menstruation period. This verse put to an end the atrocious custom of secluding the wife totally during menstruation.