Sunan Ibn Majah 790
سنن ابن ماجه#790SahihIt was narrated that Ubayy bin Ka'b said:"The Messenger of Allah said: 'The prayer of a man in congregation is higher than his prayer on his own by twenty-four or twenty-five levels
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniSahih
Muhammad Fouad Abd al-BaqiSahih
Zubair Ali ZaiHasan
In-book reference: 4:56