Commentary for Genesis 6:22

ויעש נח THUS DID NOAH — This refers to the building of the Ark (Genesis Rabbah 31:14).

AND NOAH DID THUS; ACCORDING TO ALL THAT G-D HAD COMMANDED HIM, meaning that he constructed the ark and gathered the food. Scripture’s intent in saying, And Noah did… so did he, is to explain that he did not omit a thing from all that G-d had commanded him.

ויעש נח, Noach built the ark in accordance with all the instructions given to him by G’d. He built its dimensions of length, width and height exactly as he had been commanded. He built the many cabins, and collected the various types of plants and fruit to serve as food for the journey.