Ubayy ibn Ka'b

One of the first citizens of Madinah to embrace Islam, he served as scribe to Prophet Muhammed, was one of the first to commit the Quran to writing, and belonged to the group of about two dozen who knew the entire Quran by heart when the Prophet died. Regarded as a conscience to the Muslims, he later served as adviser to Caliphs Abu Bakr and Umar and was greatly respected for his honest and frank assessments.