From Sahih Bukhari (Hadith 4744):
Narrated Qais bin Ubad:`Ali said, "I will be the first to kneel before the Beneficent on the Day of Resurrection because of the dispute." Qais said; This Verse: 'These two opponents (believers and disbelievers dispute with each other about their Lord,' (22.19) was revealed in connection with those who came out for the Battle of Badr, i.e. `Ali, Hamza, 'Ubaida, Shaiba bin Rabi`a, `Utba bin Rabi`a and Al-Walid bin `Utba
Reference: Bukhari 4744