Abu Hurayrah (may Allah be pleased with him) said that he (peace and blessings be upon him) said: "There was a prostitute of the Children of Israel. She saw a dog panting with thirst, so she took off her shoe, filled it with water and gave the dog to drink, and Allah forgave her."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النفقات / 15819