Narrated Abu Huraira: The Prophet said, "While a dog was going round a well and was about to die of thirst, an Israeli prostitute saw it and took off her shoe and watered it. So Allah forgave her because of that good deed."
— Sahih Bukhari, Volume 4, Book 56: Virtues and Merits of the Prophet (pbuh) and his Companions, Hadith #673