Yalkut Shimoni on Torah 52:1

"Make yourself an ark of gopher wood" (Genesis 6:14). In four places this expression is stated; in three it was explained, in one it was not explained. "Make yourself an ark of gopher wood" - wood of the kardus tree. "Make yourself swords of flint" (Joshua 5:2) - blades of rock. "Make yourself two trumpets of silver" (Numbers 10:2) - explained. "Make yourself a fiery serpent" (Numbers 21:8) - not explained. "The wise man will hear and increase learning" (Proverbs 1:5) - this is Moses. He said: If I make it of gold, this word does not match that word [nachash, serpent, does not echo zahav, gold]; and likewise of silver. Rather, I will make it of copper, because this word matches that word [nechoshet echoes nachash]. "And Moses made a serpent of copper" (Numbers 21:9). From here we learn that the Torah was given in the holy tongue, and just as it was given in the holy tongue, so the world was created in the holy tongue. Have you ever in your days heard one say gini, ginya, anthropi, anthropta, gever, gevarta? Rather, "man" [ish] and "woman" [ishah, which share a root] - from here that it was created in the holy tongue. "Make compartments for the ark" (Genesis 6:14) - just as the nest [ken] purifies the leper, so your ark [tevah] purifies you.