`Abdullah bin Az-Zubair:
A group of Bani Tamim came to the Prophet (and requested him to appoint a governor for them). Abu
Bakr said, "Appoint Al-Qaqa bin Mabad." `Umar said, "Appoint Al-Aqra' bin Habeas." On that Abu
Bakr said (to `Umar). "You did not want but to oppose me!" `Umar replied "I did not intend to oppose
you!" So both of them argued till their voices grew loud. So the following Verse was revealed:
'O you who believe! Be not forward......' (49.1)