Musnad Abu Ya'la al-Mawsili 3:152

Ubayd Allah ibn Umar narrated to us, Abd al-Rahman ibn Mahdi narrated to us, he said: Isra'il narrated to us, from Abu Ishaq, from Harithah ibn Mudarrib, from Ali, who said: When the intensity of battle arrived on the day of Badr, we sought protection through the Messenger of Allah, may Allah bless him and grant him peace. He was among the most intense of people, and there was no one closer to the polytheists than him.