אֵ֚יךְ נֶחְפְּשׂ֣וּ עֵשָׂ֔ו נִבְע֖וּ מַצְפֻּנָֽיו׃
װי איז דורכגעזוכט געװאָרן עֵשָׂו, אַנטפּלעקט געװאָרן זײַנע באַהעלטענישן!
Rambam
And the Ox implies the legs of the Ox, as it's said, it damages what it tramples and it breaks what it breaks and ruins in the way of his walking with his legs. And the 'Maaveh' implies the tooth (of the Ox), and its damage is the result of his eating what he eats from it. It's called with this name from its action since it uproots and seeks what it eats, as it says (Obadiah 1:6): How uprooted is Esau, how sought out (Maaveh) his hidden things.
Bartenura
והמבעה – this is the tooth, for the animal ate in the field of his fellow as it states (Exodus 22:4): “and so allows a field or vineyard to be grazed bare in another’s land,” and the tooth is called מבעה/damaging the crop because it sometimes is covered and sometimes uncovered/revealed, from the language (Obadiah 1:6): ”How ransacked his hoards!”/”Its hidden treasures were laid bare” (made empty, which refers to eating up – see the comment of Shmuel in Talmud Bava Kamma 3b), as we translate into Aramaic: the hidden object is revealed; and it is a derivative of the tooth, the animal scratching itself against a wall for her gratification (see Talmud Bava Kamma 3a) in the manner of animals scratching themselves, and when she broke the wall or soiled (with excrements, secretions) the fruits (by rolling in them) when she scratched herself on them for her gratification.
Bartenura
שלש אבעיות ביום – three times the owner revealed/exposed and appeared in his field in order that the poor could take Peah. The word אבעיות – means revealing (Obadiah 1:6): “[How thoroughly rifled is Esau,] How ransacked his hoards!” We translate this [in Aramaic] as revealing a hidden object.
Rashi
revealed in a fortified wall Revealed to enter thereby the walls of your fortification. נִבְעֶה is an expression of revealing, as in Obadiah (1:6): “His hidden things were revealed (נִבְעוּ).” Dunash, however, interprets נִבְעֶה as a protrusion, since the wall develops blisters (אֲבַעְבּוּעוֹת) because of the rains and the deterioration of the weak mortar.