Ibn Ishaq narrates: Sayyiduna Amr bin al-As, Sayyiduna Khalid bin al-Walid and Sayyiduna Uthman bin Talhah (may Allah be pleased with them) accepted Islam in the presence of the Negus (al-Najashi); then they came to Madinah in Safar in the eighth year after the Hijrah.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 8362