"I said: 'O Messenger of Allah, my mother has died; shall I give in charity on her behalf?' He said: 'Yes.' I said: 'What kind of charity is best?' He said: 'Providing drinking water.'" (Using translation from Nasāʾī 3664)
أَنَّهُ أَتَى النَّبِيَّ ﷺ فَقَالَ يَا رَسُولَ اللهِ إِنَّ أُمِّي مَاتَتْ أَفَأَتَصَدَّقُ عَنْهَا؟ قَالَ «نَعَمْ» قَالَ فَأَيُّ الصَّدَقَةِ أَفْضَلُ؟ قَالَ «سَقْيُ الْمَاءِ»