Zakat (Kitab Al-Zakat) 
Dawud :: Book 9 : Hadith 1677
Narrated Sa'd ibn Ubadah:
Sa'd asked: Apostle of Allah, Umm Sa'd has died; what form of sadaqah is best? He replied: Water (is best). He dug a well and said: It is for Umm Sa'd.
Zakat (Kitab Al-Zakat)
Dawud :: Book 9 : Hadith 1677
Narrated Sa'd ibn Ubadah:
Sa'd asked: Apostle of Allah, Umm Sa'd has died; what form of sadaqah is best? He replied: Water (is best). He dug a well and said: It is for Umm Sa'd.