Qays bin Abbad (may Allah have mercy on him) said: I heard Abu Dharr (may Allah be pleased with him) swearing an oath that this verse, "These are two disputants who disputed concerning their Lord" [Surah al-Hajj: 19], was revealed about those who engaged in single combat on the day of Badr: Hamzah (may Allah be pleased with him), Ali (may Allah be pleased with him) and Ubaydah bin al-Harith (may Allah be pleased with him), and Utbah and Shaybah, the two sons of Rabi'ah, and al-Walid bin Utbah.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 18341