Ex 17:6

17:6 I will stand before you. An astonishing statement. Man stands before God, not God before man (Deut. 19:17; 25:1–3; 17:8–13). In this trial God takes the place of the accused, standing in the dock.

on the rock. God stands on the rock and is identified with it. God is called the “Rock” in the song of Moses (Deut. 32:4, 15, 18, 31) and in the psalms that speak of this event (Ps. 78:35; 95:1).

strike the rock. Moses lifts the rod of judgment and strikes the rock on which God stands and with which He is symbolically identified. God is not guilty, but He bears the judgment. The fearful solemnity of Moses’ blow appears when he later strikes the rock in disobedience, thereby dishonoring the holiness of God (Num. 20:9–12). The rock at Massah, struck for God’s people, is a type of Christ, the incarnate and blameless Son of God, who endured the punishment for sin (1 Cor. 10:4).

water. The ultimate reference is to the water of life that flows from the throne of God (Zech. 13:1; 14:8; Ezek. 47:1–12). Jesus offers this water where it was symbolically poured out in the temple at the feast (John 7:37), and John notes the water that flowed from His pierced side on the Cross (John 19:34; cf. 7:38).