Musannaf Ibn Abi Shayba 16:384

Abu Bakr narrated to us, he said: Mu'awiyah ibn Hisham narrated to us, he said: Sufyan narrated to us, from Muharib ibn Dithar, from Jabir ibn Abdullah, from the Prophet, peace and blessings of Allah be upon him, he said: "The best of condiments is vinegar."