Imām Al-Bukhārī reports in his Ṣaḥīḥ, in the chapter entitled The virtue of one who prays [at night] in Ramaḍān, from ʿAbd Al-Raḥmān b. ʿAbdin Al-Qārī:

I went out to the mosque with ʿUmar b. Al-Khattāb one night in Ramaḍān, and we found people in separate groups: some men praying by themselves and others praying with a small group behind them. ʿUmar said, “I think if I gathered them behind one reciter it would be better.” Later, he made up his mind and gathered them behind Ubay b. Ka’b. On another night, I went out with him again and the people were praying behind their reciter [Ubay]. ʿUmar said, “What a good innovation (bid’ah) this is, but what they are missing by sleeping is better than what they are staying up to pray.” He meant the last part of the night, for the people used to pray in the early part.

This is further clarified by the more detailed report in Ibn Sa’d’s Al-Ṭabaqāt Al-Kubrā Vol.5 p42 from Nawfal b. Iyās Al-Hudhalī:

During the time of ʿUmar b. Al-Khattāb, we used to pray in Ramaḍān in groups – here and there – in the mosque. People would incline to pray behind those who had the best voices. ʿUmar said, “Do I not see that they are treating the Qurān like song? By Allāh, if I can, I will change this.” Only three nights later, he told Ubay b. Ka’b to lead them in prayer, then stood behind the rows and said, “If this is a bid’ah, then what a good bid’ah it is.”

Al-‘Allāmah Al-Mu’allimī Al-Yamānī graded this narration’s chain of transmission ṣaḥīḥ in his treatise Qiyāmu Ramaḍān p51.

Points to note

• We are reminded through this narration to avoid falling into the same problems that ʿUmar sought to solve by appointing a single imām during his Caliphate:
  • The appearance of splitting and schism, which Islam disapproves of
  • Distracting each other by reciting audibly at the same time in the mosque, reciting over each other
  • Preferring imāms and reciters for having nice voices even though others may know more Qurān and be more qualified to lead
• Scholars point out that the statement ‘what a good bid’ah this is’ does not affirm that there is any such thing as a good bid’ah in a religious sense, because innovation in religion is unconditionally and unequivocally blameworthy in the texts of ḥadīth and countless statements of the Salaf. This statement is therefore taken to mean that ʿUmar meant that what he saw was a good development – a bid’ah in the linguistic sense of something new – relative to the situation before he appointed a single imām. This meaning is also clear from the fact that night prayer in congregation in Ramaḍān already has a precedent from Allāh’s Messenger – Allāh’s peace and blessings be upon him.
• Having said that, the report in Ibn Sa’d, ‘if this is a bid’ah, then what a good bid’ah it is’ evidences that ʿUmar never called it a bid’ah in the first place, but was being rhetorical, as suggested by Shaykh Al-Mu’allimī in Qiyām Ramaḍān, in the same way as intended in Sūrah Al-Zukhruf, verse 81, “Say, if Al-Raḥmān has a son, then I am the first of the worshippers.’”

And Allāh knows best.