Abu Sufyan said: I heard Sayyiduna Jabir (may Allah be pleased with him) say: I heard the Prophet (peace and blessings be upon him) saying: "Indeed, the difference between the believer and the disbeliever and polytheist is abandoning the prayer."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب صلاة الاستسقاء / 6495