Musannaf Ibn Abi Shaybah 36163 — Book of History

Amir said: I asked Sayyiduna Ibn Abbas (may Allah be pleased with them both): Who was the first to become a Muslim? Sayyiduna Ibn Abbas (may Allah be pleased with them both) said: Have you not heard the verses of Sayyiduna Hassan bin Thabit (may Allah be pleased with him): When you wish to mention a trustworthy brother, then mention Sayyiduna Abu Bakr and his great deeds. After the Messenger of Allah (peace and blessings be upon him), he is the best of all creation, the most pious, the most just and the most faithful in keeping his word. He is second in rank and station, and first in affirming the truth of the Messengers.