Sahih Bukhari Volume 009, Book 092, Hadith Number 405.
Hadith Section/Book: Sahih Bukhari Sahih Bukhari Book 92. Holding Fast to the Qur'an and Sunnah
Narrated By Ibn Abi Mulaika : Once the two righteous men, i.e., Abu Bakr and 'Umar were on the verge of destruction (and that was because): When the delegate of Bani Tamim came to the Prophet, one of them (either Abu Bakr or 'Umar) recommended Al-Aqra' bin Habis At-Tamimi Al-Hanzali, the brother of Bani Majashi (to be appointed as their chief), while the other recommended somebody else. Abu Bakr said to 'Umar, "You intended only to oppose me." 'Umar said, "I did not intend to oppose you!" Then their voices grew louder in front of the Prophet whereupon there was revealed: 'O you who believe! Do not raise your voices above the voice of the Prophet... a great reward.' (49.2-3) Ibn Az-Zubair said, 'Thence forward when 'Umar talked to the Prophet, he would talk like one who whispered a secret and would even fail to make the Prophet hear him, in which case the Prophet would ask him (to repeat his words)."