Al Baqarah, 234 Ayah
2:234
وَٱلَّذِينَ يُتَوَفَّوۡنَ مِنكُمۡ وَيَذَرُونَ أَزۡوَٰجٗا يَتَرَبَّصۡنَ بِأَنفُسِهِنَّ أَرۡبَعَةَ أَشۡهُرٖ وَعَشۡرٗاۖ فَإِذَا بَلَغۡنَ أَجَلَهُنَّ فَلَا جُنَاحَ عَلَيۡكُمۡ فِيمَا فَعَلۡنَ فِيٓ أَنفُسِهِنَّ بِٱلۡمَعۡرُوفِۗ وَٱللَّهُ بِمَا تَعۡمَلُونَ خَبِيرٞ ٢٣٤
Wa Al-Ladhīna Yutawaffawna Minkum Wa Yadharūna 'Azwājāan Yatarabbaşna Bi'anfusihinna 'Arba`ata 'Ash/hurin ۖ Wa `Ashrāan Fa'idhā Balaghna 'Ajalahunna Falā Junāĥa `Alaykum Fīmā Fa`alna Fī 'Anfusihinna ۗ Bil-Ma`rūfi Wa Allāhu Bimā Ta`malūna Khabīrun
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 Allah is [fully] Acquainted with what you do.