Musnad Ahmad Hadith 21644

It is narrated from Zaid bin Thabit (may Allah be pleased with him) that Siddiq Akbar (may Allah be pleased with him) sent a messenger to me at the time of Yamama and called me. When I arrived, Umar Farooq (may Allah be pleased with him) was also sitting there. Siddiq Akbar (may Allah be pleased with him) said to me, "O Zaid bin Thabit! You are a wise young man, and we do not suspect you of anything. You used to write down revelation during the time of the Prophet (ﷺ). Gather the Qur'an by searching for it and compile it in one place." Zaid (may Allah be pleased with him) says, "By Allah! If they had ordered me to move a mountain from its place, it would not have been heavier for me than this command to compile the Qur'an. I said to them, 'Do you want to do something which the Prophet (ﷺ) did not do?' Siddiq Akbar (may Allah be pleased with him) said, 'By Allah! There is goodness in it.' Then they kept insisting on me until Allah opened my heart for the task, just as He had opened the hearts of Siddiq Akbar (may Allah be pleased with him) and Farooq Azam (may Allah be pleased with him)."