Job 40:15

Now behold the behemoth that I made with you; he eats grass like cattle.

The word “behemoth” is a generic term for a very large animal as well as the name of a mythical creature of gargantuan proportions. The Ibn Ezra gives two explanations for what it means that G-d made the behemoth “with” man. The first is that the behemoth dwells on land alongside man, as opposed to the leviathan, later in this same chapter, who lives in the sea. The other reason is that the behemoth, being a land-dwelling mammal, was created on the sixth day of creation, the same as man.