Commentary for Obadiah 1:3

who dwell in the clefts of the rock—Who relies on the support of his ancestors, Abraham and Isaac, but they shall not avail him. the clefts Heb. חַגְוֵי. Cf. (Isa. 19:17) “And the land of Judah shall be to Egypt for a dread (לְחָגָּא),” frayteyne [or fraite] in O.F., a cleft of a rock. And do not wonder about the “vav” of (Gen. 21:16) “like a shot (כִּמְטַחֲוֵי) ;” in which there is no radical in the word but the “teth” and the “heth.”

זדון לבך השיאך "Your arrogant heart has turned you" meaning that now that you have become great and a mighty ruler when you came to the Mt Seir, therefore, the arrogance in your heart has turned you to become too prideful.

שוכני"dwelling" as if to say you dwell in the clefts of the rock meaning that nobody can come close to you. It is as if his dwelling place was in a high place and therefore he thinks in his heart who will be able to bring me down to the lowliness on the land.