It is narrated from Sayyiduna Ibn Mas'ud (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "The superiority of prayer in congregation over prayer performed alone is more than twenty degrees."
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 3564
Hadith Gradingحکم دارالسلام:صحيح لغيره، وهذا إسناد ضعيف، عطاء بن السائب مختلط - قد توبع