Musnad Abu Ya'la al-Mawsili 155:195

Abu Bakr ibn Abi Shaybah narrated to us, Abu Khalid narrated to us, from Hisham, from Muhammad, from Abu Hurayrah, from the Prophet (peace be upon him): That a prostitute woman saw a dog on a hot day circling a well, having lolled out its tongue from thirst. So she drew water for it with her leather sock, and she was forgiven.