Musannaf Ibn Abi Shayba 27:474

Mu'awiyah ibn Hisham narrated to us, he said: Qays narrated to us, from Salamah ibn Kuhayl, from Abu Sadiq, from 'Ulaym, from Salman, who said: "Indeed, the first of this nation to arrive at the watering place of its Prophet is the first of them in Islam: Ali ibn Abi Talib."