The Quran is believed by Muslims to be God's own divine speech providing a complete code of conduct across all facets of life. This has led Muslim theologians to fiercely debate whether the Quran was "created or uncreated." According to tradition, several of Muhammad's companions served as scribes, recording the revelations. Shortly after Muhammad's death, the Quran was compiled on the order of the first caliph Abu Bakr (r. 632–634) by the companions, who had written down or memorized parts of it. Caliph Uthman (r. 644–656) established a standard version, now known as the Uthmanic codex, which is generally considered the archetype of the Quran known today. There are, however, variant readings, with mostly minor differences in meaning.