Musannaf Ibn Abi Shaybah 32447 — Book of Faith

Abu Sadiq (may Allah have mercy on him) said that Sayyiduna Ali (may Allah be pleased with him) said: Islam has three supports: faith, prayer and the congregation. So no prayer will be accepted without faith. Whoever has believed will pray, and whoever prays will be with the congregation. And whoever separates from the congregation even by the distance of a handspan has taken the collar of Islam off his neck.