Musnad Ahmad 5:478

'Abd al-Rahman narrated to us, from Isra'il, from Abu Ishaq, from Harithah ibn Mudarrib, from 'Ali, who said: "When the fighting became intense on the day of Badr, we sought protection behind the Messenger of Allah, peace and blessings of Allah be upon him. He was among the most intense of the people; there was no one closer to the polytheists than him."