Narrated 'Abdullah bin Az-Zubair:
"Al-Aqra' bin Habis arrived to meet the Prophet (ﷺ)" - he said - "so Abu Bakr said: 'O Messenger of Allah! Appoint him over his people.' 'Umar said: 'Do not appoint him O Messenger of Allah!' They continued talking before the Prophet (ﷺ) until they raised their voices. Abu Bakr said to 'Umar: 'You only wanted to contradict me.' So ['Umar] said: 'I did not want to contradict you.'" He said: "So this Ayah was revealed: 'O you who believe! Do not raise your voices above the voice of the Prophet (49:2).'" He said: "After that, when 'Umar spoke before the Prophet (ﷺ), his speech could not be heard until he told him he could not understand him." He (one of the narrators) said: "And Ibn Az-Zubair did not mention his grandfather" meaning Abu Bakr. (ES)
English reference (ES): Vol. 5, Book 44, Hadith 3266 (ES)
Arabic reference (ES): Book 47, Hadith 3576 (ES)