This is Arabic for "I am the Truth." It is one of the most famous examples of "Shat'ha," or ecstatic exclamation. These utterances are made during fana, (Arabic for "annihilation"), meaning annihilation of the self through mystical union with God. Stating "I am the Truth" indicated that al-Hallaj had discovered his non-duality with Allah. For saying it out loud, he was executed for heresy.