Abdullah bin Mas'ud (may Allah be pleased with him) said: The Messenger of Allah (peace and blessings be upon him) sent us to the Negus (al-Najashi), and we were 80 men; with us was Ja'far bin Abi Talib (may Allah be pleased with him) as well. He mentioned the complete hadith about their entering the court of the Negus, and at its end it says that Ibn Mas'ud (may Allah be pleased with him) hastened to come back, and he also took part in Badr.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3919