וַיִּגְדַּ֖ל הָאִ֑ישׁ וַיֵּ֤לֶךְ הָלוֹךְ֙ וְגָדֵ֔ל עַ֥ד כִּֽי־גָדַ֖ל מְאֹֽד׃
그 사람이 창대하고 왕성하여 마침내 거부가 되어
Rashi on Genesis
כי גדל מאד UNTIL HE BECAME VERY GREAT — so that people used to say, “Rather the dung of Isaac’s mules than all Abimelech’s gold and silver’’(Genesis Rabbah 64:7).
Malbim on Genesis
The man prospered. Scripture attributes this prosperity to Yitzchok’s own merit rather than to the bounty of the land. He continued to prosper. He never suffered a setback, which demonstrated that his prosperity was not by chance. Until he became very great. If his prosperity had been the result of favorable circumstances it would have reached a limit and then been followed by a downturn.