Silsilat al-Ahadith al-Sahihah

It is narrated from Sayyiduna Abu Hurairah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: “(Once) a man was walking on the road when he became extremely thirsty. He found a well, so he went down into it and drank water, then came out. There was a dog there, panting and licking the mud out of thirst. The man said (to himself): ‘This dog has been afflicted by thirst just as I was.’ So he (again) went down into the well, filled his sock with water, held it in his mouth, climbed up, and gave the dog water to drink. Allah the Exalted appreciated his action and sincerity, and forgave him.” (Upon hearing this) the Companions said: “O Messenger of Allah! Is there a reward for us in (showing mercy to) animals as well?” He (peace and blessings be upon him) said: “(Yes,) there is a reward for serving and caring for every living being with a moist liver.”

It is narrated from Sayyiduna Abu Hurairah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Once a dog was circling around a well, thirst was about to kill it. Suddenly, one of the immoral women from among the women of Bani Israel saw it. She took off her shoe and, using it, drew water from the well and gave it to the dog to drink. Because of this action, she was forgiven."