The Messenger of Allah ﷺ said, "The superiority of a man's prayer in congregation over his prayer alone is some twenty-odd degrees."
حدثنا محمد بن فضيل حدثنا عطاء بن السائب عن أبي الأحوص
قال رسول الله ﷺ فضل صلاة الرجل في الجماعة على صلاته وحده بضع وعشرون درجة
Its isnad is hasan, because Muhammad bin Fudayl was among those who heard from Ata bin Saaib later on. The hadith is in Targheeb 1:150, where he said, Ahmad narrated it with a hasan isnad, and Abu Yaala, Bazzar, Tabarani, and Ibn Khuzayma in his Sahih narrated something similar. It is also in Majma al-Zawaid 2:38, where he attributed it to them except Ibn Khuzayma, and said, the men of Ahmad are trustworthy. It will come again with a sahih isnad at 3567.