וַיֹּ֥אמֶר אֲבִימֶ֖לֶךְ אֶל־יִצְחָ֑ק לֵ֚ךְ מֵֽעִמָּ֔נוּ כִּֽי־עָצַֽמְתָּ־מִמֶּ֖נּוּ מְאֹֽד׃
Lalu Abimelekh berkata kepada Ishak, “Pergilah dari tengah-tengah kami, sebab engkau telah menjadi jauh lebih kuat daripada kami.”
Chizkuni
לך מעמנו, “go from us;” they argued that the reason they wanted him to leave was that they felt their land had not been blessed due to the famine, as opposed to the piece of land on which Yitzchok had brought forth such an exceptionally good harvest. They assumed that as soon as Yitzchok would vacate the land he had worked they would appropriate it for themselves and reap the benefits.
Sforno
כי עצמת ממנו, you would be able to stage a rebellion against us using all your wealth.
Or HaChaim
כי עצמת ממנו, "for you have become more powerful than we." Even the wealth and authority of the king paled into insignificance compared to the reputation of Isaac. There is no greater humiliation for a king than to be ranked lower than some other resident in his domain.