Yahya related to me from Malik from Sumayy, the mawla of Abu Bakrfrom Abu Salih as-Samman from Abu Hurayra that the Messenger of Allah,may Allah bless him and grant him peace, said, "A man was walking on aroad when he became very thirsty. He found a well and went into it anddrank and came out. There was a dog panting and eating earth out ofthirst. The man said, 'This dog has become as thirsty as I was.' Hewent down into the well and filled his shoe and then held it in hismouth until he climbed out and gave the dog water to drink. Allahthanked him for it and forgave him." They said, "Messenger of Allah,do we have a reward for taking care of beasts?" He said, "There is areward for every one with a moist liver."
USC-MSA web (English) reference: Book 49, Hadith 23
Arabic reference: Book 49, Hadith 1696