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Discontented with life around him, he retreated to a cave in the surrounding mountains for meditation and reflection. It was here, at age 40, is when he received his first revelation from God. Three years after this event he started preaching these revelations publicly, proclaiming that "God is One", that complete "surrender" to Him is the only way acceptable to God, and that he himself was a prophet and messenger of God.
Who is The Prophet Muhammad