The Cow - 2:231
When you divorce women, when they have finished their waiting period, either keep them with you in kindness or let them go in kindness. Do not keep them in such a way as to harm them in revenge. He who does that is wronging himself. Do not take the signs of Allah lightly. Think of Allah´s favors which He has bestowed upon you and of the Book and the wisdom which He has sent down to you for your admonition. Listen to Allah and know that Allah is All-Knowing.
What is the waiting period for a woman if her husband dies?
The Cow/2:234
The wives left behind by the men who die among you wait four months and ten (days). When they have fulfilled their term, there is no responsibility on you to do what is suitable for them. Allah is All-Knowing of what you do.