Midrash su Genesi 26:33

Rabbi ' Aḳiba said: Every place where our forefathers went, the well went in front of them, and they dug three times and found it before them. Abraham dug three times and found it before him, as it is said, "And Isaac digged again the wells of water, which they had digged in the days of Abraham" (Gen. 26:18). And Isaac dug in the land (of Canaan) four times, and found it before him, as it is said, "And Isaac's servants digged in the valley" (Gen. 26:19). And it is written about Jerusalem, "And it shall come to pass in that day, that living waters shall go out from Jerusalem" (Zech. 14:8). This refers to the well which will arise in Jerusalem in the future, and will water all its surroundings. Because they found (the well) seven times, he called it Shib'ah (seven).