Al-Baqarah 2:234

Wallatheena yutawaffawnaminkum wayatharoona azwajan yatarabbasnabi-anfusihinna arbaAAata ashhurin waAAashran fa-ithabalaghna ajalahunna fala junaha AAalaykum feemafaAAalna fee anfusihinna bilmaAAroofi wallahubima taAAmaloona khabeer

And those who are taken in death among you and leave wives behind - they, [the wives, shall] wait four months and ten [days]. And when they have fulfilled their term, then there is no blame upon you for what they do with themselves in an acceptable manner. And Allāh is [fully] Aware of what you do.

Those among you who pass away and leave wives behind, their wives keep themselves waiting for four months and ten days. So, when they have reached (the end of) their waiting period, there is no sin on you in what they do for themselves in recognized manner. Allah is All-Aware of what you do.