Or HaChaim on Leviticus 26:42/אור החיים על ויקרא כ״ו:מ״ב

1 וזכרתי את בריתי יעקוב, "And I will remember My covenant, the one with Jacob, etc." The Torah announces here that whereas the confession of their guilt helps to reduce the severity of the afflictions to which G'd subjects the Jewish people, G'd has to invoke the merit of the patriarchs in order to restore them to their former status

2The verse also supplies an additional reason for G'd having driven the Jewish people into exile into the land of their enemies. The abuse the people would be subjected to there will become the catalyst that will make G'd remember the merit of the patriarchs. In addition, G'd will remember the sad state of the Holy Land while its people are absent. If G'd had not first exiled the Jews He would not have any reason to remember the land itself with special kindness. As it is, the sequence וזכרתי את בריתי….והארץ אזכר makes perfect sense.

3את בריתי יעקוב, if the merit of Jacob suffices, all well and good; if not G'd will also invoke the merit of Isaac, etc.