"My mother died unexpectedly; if she had been able to speak she would have given charity. Should I give charity on her behalf?" The Messenger of Allah said: "Yes." So he gave charity on her behalf.  

لِرَسُولِ اللَّهِ ﷺ إِنَّ أُمِّي افْتُلِتَتْ نَفْسُهَا وَإِنَّهَا لَوْ تَكَلَّمَتْ تَصَدَّقَتْ أَفَأَتَصَدَّقُ عَنْهَا فَقَالَ رَسُولُ اللَّهِ ﷺ نَعَمْ فَتَصَدَّقَ عَنْهَا  

"Sa'd bin 'Ubadah went out with the Prophet on one of his campaigns, and death came to his mother in Al-Madinah. It was said to her (as she was dying): 'Make a will.' She said: 'To whom shall I make a will? The wealth belongs to Sa'd.' Then she died before Sa'd came. When Sa'd came, he was told about that and he said: 'O Messenger of Allah, will it benefit her if I give in charity on her behalf?' The Prophet said: 'Yes.' Sa'd said: 'Such and such a garden is given in charity on her behalf' -regarding a garden that he named."  

خَرَجَ سَعْدُ بْنُ عُبَادَةَ مَعَ النَّبِيِّ ﷺ فِي بَعْضِ مَغَازِيهِ وَحَضَرَتْ أُمَّهُ الْوَفَاةُ بِالْمَدِينَةِ فَقِيلَ لَهَا أَوْصِي فَقَالَتْ فِيمَ أُوصِي الْمَالُ مَالُ سَعْدٍ فَتُوُفِّيَتْ قَبْلَ أَنْ يَقْدَمَ سَعْدٌ فَلَمَّا قَدِمَ سَعْدٌ ذُكِرَ ذَلِكَ لَهُ فَقَالَ يَا رَسُولَ اللَّهِ هَلْ يَنْفَعُهَا أَنْ أَتَصَدَّقَ عَنْهَا فَقَالَ النَّبِيُّ ﷺ نَعَمْ فَقَالَ سَعْدٌ حَائِطُ كَذَا وَكَذَا صَدَقَةٌ عَنْهَا لِحَائِطٍ سَمَّاهُ