A man said to the Prophet ﷺ, "My mother died suddenly and I thought that if she had lived she would have given alms. So, if I give alms now on her behalf, will she get the reward?" The Prophet ﷺ replied in the affirmative.  

لِلنَّبِيِّ ﷺ إِنَّ أُمِّي افْتُلِتَتْ نَفْسُهَا وَأَظُنُّهَا لَوْ تَكَلَّمَتْ تَصَدَّقَتْ فَهَلْ لَهَا أَجْرٌ إِنْ تَصَدَّقْتُ عَنْهَا قَالَ نَعَمْ  

A man said to the Prophet, "My mother died suddenly, and I think that if she could speak, she would have given in charity. May I give in charity on her behalf?" He said, "Yes! Give in charity on her behalf."  

لِلنَّبِيِّ ﷺ إِنَّ أُمِّي افْتُلِتَتْ نَفْسَهَا وَأُرَاهَا لَوْ تَكَلَّمَتْ تَصَدَّقَتْ أَفَأَتَصَدَّقُ عَنْهَا قَالَ نَعَمْ تَصَدَّقْ عَنْهَا  

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).  

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ إِذَا مَاتَ الإِنْسَانُ انْقَطَعَ عَنْهُ عَمَلُهُ إِلاَّ مِنْ ثَلاَثَةٍ إِلاَّ مِنْ صَدَقَةٍ جَارِيَةٍ أَوْ عِلْمٍ يُنْتَفَعُ بِهِ أَوْ وَلَدٍ صَالِحٍ يَدْعُو لَهُ