Commento su Genesi 26:13

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).

ויגדל, in material wealth and all types of possessions.

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.

So that people would say: Rather the dung of Yitzchok’s mules... Otherwise why does it say, “Until he became very great”? [The next verse details his wealth! Perforce,] it comes to tell us the extent [of his blessing]. Thus Rashi mentions mules, since mules [ordinarily] have no blessing at all, as Rashi explained in Devarim 15:14.

ויגדל האיש, nicht ויגדל, auch nicht ויגדל יצחק, sondern ויגדל האיש es ist dies ganz aus der Anschauung der Philister gesprochen: es ward ihnen der Mann zu groß und dadurch nicht nur ihr Neid, sondern auch ihre Eifersucht erregt. Ganz ebenso bei Jakob in Beziehung zu Labans Söhnen: ויפרץ האיש. (erst. B. M. 30,43)10

הלוך וגדל the word הלוך is an infinitive mode of the verb, whereas the word גדל is an adjective or also an infinitive.. We encounter a parallel construction in Exodus 12,9 ובשל מבושל. The meaning of the phrase is that Yitzchok’s wealth kept on increasing and he kept on becoming a man of great substance until he had reached a point where he could be described as גדול מאד, “very great.”