Exodus 24:10

and they saw the God of Israel, who revealed Himself to them in some form which gave them an idea of His divine essence; and there was under His feet as it were a paved work of a sapphire stone, a brilliant formation of sapphire blue, and as it were the body of heaven in his clearness. It was a vision of the covenant God of Israel, of Him who had first revealed Himself to the patriarchs, in all the beauty of His grace and faithfulness. Thus the fellowship, the alliance, of the children of Israel with the majestic God was perfected.