Midrasch zu Schemot 14:22

When He desired it to happen, He said: Let the waters under the heavens be gathered together (Gen. 1:9). And when He was so inclined, He made the sea become dry and turn into land, as is said: And the children of Israel went into the midst of the sea, upon the dry ground (Exod. 14:22). Therefore, whatsoever the Lord pleased, that hath He done, etc. With regard to the heavens, it is said: Stretch forth thy hand toward heaven that there may be hail (ibid. 9:22), and in reference to the earth it is stated: Stretch out thy rod, and smite the dust of the earth (ibid. 8:12). What is written above concerning this matter? For now I have stretched out My hand … But in very deed for this cause have I made thee to stand (ibid. 9:16), so that you will not die as a result of the first plague, and so that My name may be declared throughout all earth (ibid., v. 36).