Tosefta zu Bereschit 26:24

Rebbi Dostai Bar Yanai says in the name of Rebbi Meir, ‘It says [in the Torah] regarding Yitzchak “… and I will bless you and I will make your seed abundant for the sake of Avraham, My servant.” (Genesis 26:24) Yitzchak expounded and said, “A blessing only settles [on a person] through physical deeds.” [Then] he got up and he planted [seeds in the field], as it says, “And Yitzchak planted in that land, and he founded in that year Mea Shearim (literally: One Hundred Gates), and Hashem blessed him.” (Genesis 26:12) One hundred [is referring to] types [of seeds that Yitzchak planted. In that case why does the verse say] Mea Shearim (i.e. One Hundred Gates and not One Hundred Types of Seeds)? [Because the word Shearim is not referring to gates, but rather to measurements,] that they (i.e. Yitzchak’s workers) measured a hundred times [more than they planted]. It comes out [that] for every one [seed that they planted, they received back] a hundred [units of crops] according to what they measured.