It is narrated from Sayyiduna Ubayy bin Ka'b (may Allah be pleased with him) that he used to recite (a verse of Surah al-Fath) this way: "When those who disbelieved put in their hearts zealotry, the zealotry of the time of ignorance; and had you shown zealotry as they did, the Sacred Mosque would have been ruined; then Allah sent down His tranquillity upon His Messenger" [Surah al-Fath: 26] . This reached Sayyiduna Umar (may Allah be pleased with him) and he found it very displeasing. He sent for Sayyiduna Ubayy while he was applying medicine to one of his camels. He came to him, and Umar (may Allah be pleased with him) called a group of his companions, among whom was Sayyiduna Zayd bin Thabit (may Allah be pleased with him). Then Umar (may Allah be pleased with him) asked: Which of you recites Surah al-Fath? Sayyiduna Zayd recited it just as we recite it today. Umar (may Allah be pleased with him) showed sternness over this (variant recitation). Then Ubayy said: May I speak? He said: Speak. Ubayy said: You know that I used to go in to the Prophet (peace and blessings be upon him) and he would teach me the Qur'an while you people were at the door. Now if you wish that I teach the people just as I was taught, well and good; otherwise I will not teach a single letter for as long as I live. Sayyiduna Umar (may Allah be pleased with him) said: "No, rather, teach the people (in the same way)." This hadith is sahih (authentic) on the condition of the two Shaykhs (Bukhari and Muslim), but they did not record it.