Commentary for Isaiah 54:15

Behold, the one with whom I am not, shall fear Heb. גּוֹר יָגוּר. Behold, he shall fear and dread evil decrees, he with whom I am not, i.e., Esau. ([Mss. read:] the wicked Esau and his ilk.)

גור יגור. According to R. Jonah: they will surely gather together; comp. ממגורות barns,²⁸Lit., the places where the corn is gathered together. (Joel 1:17). The meaning of the whole verse is accordingly: Is it possible, that any alliance should be made except with my permission ? (The alliance between Gog and Magog is here referred to.)

whoever mobilizes against you Heb. גָר. Whoever mobilizes against you for war. Alternatively, מִי גָר [means:] whoever contends with you (וְנִתְגָּרֶה). And our Rabbis explained it as referring to the proselytes (גֵּרִים), [i.e.,] to say that we will not accept proselytes in Messianic times. And even according to the simple meaning of the verse it is possible to explain: whoever became sojourners with you in your poverty, shall dwell with you in your wealth. Comp. (Gen. 25:18) “In the presence of all his brethren he dwelt (נָפָל).”