Musannaf Ibn Abi Shayba 28:41

Waki’ narrated to us, he said: Sufyan narrated to us, from Salam ibn ‘Abd al-Rahman al-Nakha’i, from Abu Zur’ah ibn ‘Amr ibn Jarir, from Abu Hurayrah, he said: The Messenger of Allah (peace and blessings of Allah be upon him) used to dislike the *shikal* (a white marking on the legs) of horses.