And thou shalt say unto him,.... Upon meeting him: the Lord God of the Hebrews hath sent me unto thee; still appearing in the character of the ambassador of Jehovah, the God of the children of Israel: saying, let my people go, that they may serve me in the wilderness; the demand is once more renewed, before any punishment is inflicted for refusal, that the patience and forbearance of God might be the more visible, and his judgments appear the more righteous when inflicted, as well as Pharaoh be left more inexcusable. The reason of the demand is observed: that they may serve me; keep a feast, and sacrifice to him, as is before expressed, and the place where is pointed at: in the wilderness; at Sinai, in Arabia, where were the mountains of Sinai and Horeb; but the time of their service is not here expressed, as elsewhere, namely, three days: and, behold, hitherto thou wouldest not hear; and obey the voice of the Lord, upbraiding him with his disobedience, and the hardness of his heart; but signifying it was not now too late, though it was advisable to be quick, or the blow would be given, and the plagues inflicted.