(3) باب مَا يَلْحَقُ الإِنْسَانَ مِنَ الثَّوَابِ بَعْدَ وَفَاتِهِ
Abu Huraira (Allah be pleased with him) reported Allah's Messenger (ﷺ) as saying:
When a man dies, his acts come to an end, but three, recurring charity, or knowledge (by which people) benefit, or a pious son, who prays for him (for the deceased).
Reference: Sahih Muslim 1631
In-book reference: Book 25, Hadith 20
USC-MSA web (English) reference(deprecated numbering scheme): Book 13, Hadith 4005