Sunan Ibn Majah 789
سنن ابن ماجه#789SahihIt was narrated that Ibn 'Umar said:"The Messenger of Allah said: 'The prayer of a man in congregation is twenty-seven levels more virtuous than a man's prayer on his own
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
Shuaib Al ArnautSahih
Zubair Ali ZaiSahih Muslim
In-book reference: 4:55