Due to the fact that the Quran was revealed in disjointed verses and chapters, a point came when it needed to be gathered into a coherent whole text. There are disagreements among both Muslim and non-Muslim scholars as to when the Quran was first compiled. A hadith in Sahih Bukhari states that the caliph Abu Bakr commanded Zayd ibn Thabit to compile the written Quran, relying upon both textual fragments and the memories of those who had memorized it