Prophet Muhammad (P.B.U.H) said:
إِذَا مَاتَ الإِنْسَانُ انْقَطَعَ عَمَلُهُ إِلَّا مِنْ ثَلاَثٍ: إِلَّا مِنْ صَدَقَةٍ جَارِيَةٍ، أَوْ عِلْمٍ يُنْتَفَعُ بِهِ، أَوْ وَلَدٍ صَالِحٍ يَدْعُو لَهُ
“When a man dies, his deeds come to an end except for three things: Sadaqah Jariyah (ceaseless charity); a knowledge which is beneficial, or a virtuous descendant who prays for him (for the deceased).”
(Muslim)