Surah Al-Baqarah (The Cow), Verse 234

وَالَّذِیْنَ یُتَوَفَّوْنَ مِنْكُمْ وَیَذَرُوْنَ اَزْوَاجًا یَّتَرَبَّصْنَ بِاَنْفُسِهِنَّ اَرْبَعَةَ اَشْهُرٍ وَّعَشْرًا فَاِذَا بَلَغْنَ اَجَلَهُنَّ فَلَا جُنَاحَ عَلَیْكُمْ فِیْمَا فَعَلْنَ فِیْۤ اَنْفُسِهِنَّ بِالْمَعْرُوْفِ وَاللّٰهُ بِمَا تَعْمَلُوْنَ خَبِیْرٌ ۟

Wallazeena yutawaffawna minkum wa yazaroona azwaajai yatarabbasna bi anfusihinna arba'ata ashhurinw wa 'ashran fa izaa balaghna ajalahunna falaa junaaha 'alaikum feemaa fa'alna feee anfusihinna bilma'roof; wallaahu bimaa ta'maloona Khabeer

“If any of you die and leave widows behind, they shall wait concerning themselves four months and ten days: When they have fulfilled their term, there is no blame on you if they dispose of themselves in a just and reasonable manner. And Allah is well acquainted with what ye do.”

Quran 2:234 (Yusuf Ali Translation)