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." ʿUmar said, "Appoint Al-Aqra' bin Habeas." On that Abu Bakr said (to ʿUmar). "You did not want but to oppose me!" ʿUmar 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)
أَنَّهُ قَدِمَ رَكْبٌ مِنْ بَنِي تَمِيمٍ عَلَى النَّبِيِّ ﷺ فَقَالَ أَبُو بَكْرٍ أَمِّرِ الْقَعْقَاعَ بْنَ مَعْبَدٍ وَقَالَ عُمَرُ بَلْ أَمِّرِ الأَقْرَعَ بْنَ حَابِسٍ فَقَالَ أَبُو بَكْرٍ مَا أَرَدْتَ إِلَى أَوْ إِلاَّ خِلاَفِي فَقَالَ عُمَرُ مَا أَرَدْتُ خِلاَفَكَ فَتَمَارَيَا حَتَّى ارْتَفَعَتْ أَصْوَاتُهُمَا فَنَزَلَ فِي ذَلِكَ {يَا أَيُّهَا الَّذِينَ آمَنُوا لاَ تُقَدِّمُوا بَيْنَ يَدَىِ اللَّهِ وَرَسُولِهِ} حَتَّى انْقَضَتِ الآيَةُ