וַיִּזְרַ֤ע יִצְחָק֙ בָּאָ֣רֶץ הַהִ֔וא וַיִּמְצָ֛א בַּשָּׁנָ֥ה הַהִ֖וא מֵאָ֣ה שְׁעָרִ֑ים וַֽיְבָרֲכֵ֖הוּ יְהוָֽה׃
以撒在那地撒種,那一年就收穫了百倍;永恆者賜福給他。
Rashi
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).
Radak
ויזרע...מאה שערים, 100 times as much as they had expected to harvest from this planting.