Kabbalah sur Samuel 1 1:10

Another explanation for, "And Isaac entreated," is that by his prayer he hollowed out a passage that reached above to Mazal that bestows children. It is upon that place that giving birth to children depends, as it is written, "and she prayed to (lit. 'above') Hashem" (I Shmuel 1:10). Then, "Hashem was entreated of him." Do not pronounce it "entreated" (Heb. וַיֵּעָתֶר), but "hollowed out" (Heb. וַיֵּחָתֶר). For the Holy One, blessed be He, cleared the way and accepted the prayer. Then, "Rivkah his wife conceived."