We should not overlook the fact that the Torah records the details of the Ark’s measurements, nor should we fail to notice the Torah’s repeated mention of the fact that Noach follows every detail. Noach’s compliance with every instruction is noted with the words, kein asah, “so he did.” Horav S. R. Hirsch, zl, derives an important lesson from Hashem’s entire act of saving Noach with a select group of representatives of the world’s creatures. Hashem chose one man who was to save himself, his family and the animal world for the future, but that this man would be able to do so only if he did everything exactly in strict accordance with the commands given to him by Hashem.
Gadol metzuvah v’oseh, “Greater is one who is commanded and follows the command”: It is a basic principle in Judaism that the value of an action executed because one is commanded by G-d is greater than that which is carried out spontaneously. Contrary to the opinion of the “misguided,” only acts performed for the purpose of fulfilling Hashem’s will have true value. Acts performed impetuously, on impulse, have only uncertain, secondary significance. One hundred twenty years elapsed between Hashem’s command to Noach and the commencement of the Flood. During this time, Noach could have occupied himself with a number of things. He could have built a multitude of arks, but he built only one, and this took him one hundred and twenty years. Why? Because this is what Hashem told him to do – no more – no less. He restricted himself to doing – albeit with great accuracy and attention to the minutest detail – that which G-d had instructed him to do. The rest was up to G-d.