וַיִּפְשַׁ֣ע אֱד֗וֹם מִתַּ֙חַת֙ יַד־יְהוּדָ֔ה עַ֖ד הַיּ֣וֹם הַזֶּ֑ה אָ֛ז תִּפְשַׁ֥ע לִבְנָ֖ה בָּעֵ֥ת הַהִֽיא׃
Demikianlah Edom memberontak melepaskan diri dari kekuasaan Yehuda sampai hari ini. Kemudian Libna pun memberontak pada waktu itu juga.
Ibn Ezra
פשעו בי They have rebelled against me. They withdrew from my command (comp. 2 Kings 8:22; Exod. 22:8).11This explanation of פשע seems to be derived from the phrase פשע מתחת יד ‘to rebel ’ (2 Kings 8:22)—literally, to withdraw from the authority of—and to be supported by דבר פשע (Exod. 22:8), an object that was lost by its owner—literally, that has slipped away from its possessor. Our author, however, in his commentary to Exodus explains דבר פשע, as generally understood, an object of trespass, and contrasts with this explanation, the one above mentioned as the opinion of R. Joshua ; eventually he seems to have entirely adopted the meaning given in the text, as is also to be seen in the abridged commentary on Exodus (22:8).
Or HaChaim
Another meaning contained in the blessing may be that as long as Jacob will exercise his dominion over Esau by serving the Lord in holiness, the blessing would remain in effect; were he not to do so, one brother could never become a servant to another brother. Should Jacob (or his descendants) fail to serve the Lord, Esau would assume dominion over him. This is why we find that even a relatively mild dereliction of duty towards G'd by the kingdom of Yehudah led to Edom recovering politically (Kings II 8,22).