מדרש על בראשית 6:15

THE ARK AND THE FLOOD
"And this is how thou shalt make the ark" (Gen. 6:15). R. Shemiah taught: The Holy One, blessed be He, showed Noah with a finger and said to him, Like this and that shalt thou do to the ark. One hundred and fifty rooms were along the length at the left side of the ark, thirty-three rooms across the width in the side within, and thirty-three rooms in the side across the width on the outside; and ten compartments in the centre, which were for the storerooms for the food. And there were five protected cisterns on the right side of the ark, and fifty protected cisterns on the left side of the ark, and the openings for the water pipes opened and closed, and so was it in the lowest division; and so || on the second floor, and so on the third floor.

Rabbi Ishmael said: The five fingers of the right hand of the Holy One, blessed be He, all of them appertain to the mystery of the Redemption. He showed the little finger of the hand to Noah, (pointing out) how to make the ark, as it is said, "And this is how thou shalt make it" (Gen. 6:15). With the second finger, which is next to the little one, He smote the firstborn of the Egyptians, as it is said, "The magicians said unto Pharaoh, || This is the finger of God" (Ex. 8:19). With how many (plagues) were they smitten with the finger? With ten plagues. With the third finger, which is the third (starting from) the little finger, He wrote the tables (of the Law), as it is said, "And he gave unto Moses, when he had made an end of communing with him… tables of stone, written with the finger of God" (Ex. 31:18). With the fourth finger, which is next to the thumb, the Holy One, blessed be He, showed to Moses what the children of Israel should give for the redemption of their souls, as it is said, "This they shall give… half a shekel for an offering to the Lord" (Ex. 30:18). With the thumb and all the hand the Holy One, blessed be He, will smite in the future all the children of Esau, for they are His foes, and likewise (will He smite) the children of Ishmael, for they are His enemies, as it is said, "Let thine hand be lifted up above thine adversaries, and let all thine enemies be cut off" (Mic. 5:9).