Musannaf Ibn Abi Shayba 21:617

Abu Mu'awiyah narrated to us, from al-A'mash, from 'Amr ibn Murrah, from Abu 'Ubaydah, from 'Abdullah, who said: When Moses was sent to Pharaoh, he said: "O Lord, what should I say?" He said: "Say: *Haya Shara Haya*." He said: "The interpretation of that is: The Living before everything, and the Living after everything."