It is narrated from Hazrat Abu Hurairah (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said: Satan comes to one of you and asks, "Who created the sky?" He replies, "Allah did." Then he asks, "Who created the earth?" He says, "Allah did." Then he asks, "Who created Allah?" When any of you experiences such thoughts, he should say: "Aamantu billahi wa birusulih" (I believe in Allah and His messengers).