פּירוש אויף בראשית 26:12

בארץ ההוא IN THAT LAND although it (Gerar) had not the sacred importance of Erez Yisroel proper — i. e., as the territory of the seven nations, and is therefore not as fertile as the Holy Land (cf. Ketubot 112a).

מאה שערים, Rashi writes that our sages said that the meaning of the expression (שער(ים here is “estimate” for the sake of tithing. [Either, according to Onkelos,] Yitzchok’s harvest was 100 times as much as could be expected, or that he had to tithe 100 times as much as he had expected.

בארץ ההיא, even though the soil of this land is exceptionally hard;