In the six hundredth year of Noah's life, in the second month, on the seventeenth day of the month, on this day, all the springs of the great deep were split, and the windows of the heavens opened up. And the rain was upon the earth for forty days and forty nights. On this very day, Noah came, and Shem and Ham and Japheth, Noah's sons, and Noah's wife and his sons' three wives with them, into the ark.
The second portion of our Parsha, Sheni, deals with two events that occurred on the 17th of Cheshvan : The first was the beginning of the forty days and forty nights of rain that became the flood that annihilated civilization , and the second was the Command given to Noach בֹּֽא… אֶל הַתֵּבָ֑ה. Come to the ark.
The Hebrew root ב.ו.א "to come" appears seven times in the second reading of our parsha. When all are laughing and ridiculing him, when a storm is brewing and water is flooding the world, this is the great and difficult commandment that Noach fulfils with great belief.