Zechus Avos sustains Israel through galus

במדרש ידוע תדע גר יהי' זרעך.

In the Midrash, on the verse "Know with certainty that your offspring will be strangers" (Bereishis 15:13).

The Sefas Emes opens with the prophecy of galus given to Avraham Avinu at the bris bein habesarim, where Hashem tells him that his descendants will be strangers in a land not their own.

ידוע שאני מפזרן תדע שאני מכנסן כו'

"Know" — that I am the One who scatters them; "you shall know with certainty" — that I am the One who will gather them in.

The Midrash reads the doubled language of "knowing" as containing both halves of the same promise: the very Hashem who decrees the dispersion of galus is the One who guarantees the ingathering of geulah.

פי' שהיה אברהם אע"ה הכנה אל הגלות ואל הגאולה שלולי זכותן של האבות לא הי' לנו ח"ו תקומה בגלות מכש"כ שלא היינו ראוים לגאולה ולכן התקשר הקב"ה הגלות והגאולה באברהם כמ"ש אימה חשיכה גדולה כו' שרומז אל הד' מלכיות והרגיש בכל אלה הגליות.

The explanation is that Avraham Avinu was the hachanah (preparation) for both the galus and the geulah; for were it not for the zechus avos (merit of the forefathers), we would have had — chas v'shalom — no endurance in galus, and all the more so we would not have been worthy of the geulah. Therefore Hashem bound up the galus and the geulah within Avraham, as it is written, "a dread, a great darkness" (Bereishis 15:12), which alludes to the four kingdoms, and he felt all of these exiles.

Avraham was not merely told about galus — he became the spiritual root that makes both survival in galus and the eventual redemption possible. His own merit is the reservoir Bnei Yisrael draw upon. Hashem deliberately tied the whole arc of exile and redemption to Avraham, and the vision of "great darkness" already contained, in seed form, every later empire that would oppress his children, which Avraham personally experienced.

וכן הקדים הקב"ה לאאע"ה ואעשך לגוי גדול כו' ומקללך אאור ולמה יהי' לו מקללים רק שהראה לו הקב"ה שהוא מוכן לבנ"י להגין עליהם בכל מקומות מושבותיהם להצילם מהרודפים כמ"ש במד' כבוש הדרך לבניך.

Similarly, Hashem prefaced to Avraham Avinu, "And I will make you into a great nation… and the one who curses you I will curse" (Bereishis 12:2-3). And why would he have those who curse him? Rather, Hashem was showing him that he is prepared to be there for Bnei Yisrael, to shield them in all the places of their dwellings, to save them from their pursuers — as the Midrash says, "Conquer the road for your children."

The promise of protection against enemies seems strange for a single righteous man who had no obvious foes. The Sefas Emes explains that this blessing was really aimed at Avraham's descendants: by walking the land himself, Avraham "paved the way," embedding protective merit into every place Bnei Yisrael would later be scattered.

ואנחנו צריכים להיות בוחרים בדרכי אבותינו כמו שמבקשין אלקי אברהם אלקי יצחק פי' שחפצין לקבל אלקותו ית"ש כפי הכנת אבותינו ואז זכותם מסייע לנו לעבודת השי"ת ולהצילנו בגלות ולזכות לגאולה במהרה בימינו:

And we must be among those who choose the ways of our forefathers, just as we ask, "the God of Avraham, the God of Yitzchak" — meaning that we desire to accept His Divinity, may He be blessed, according to the hachanah (preparation) of our forefathers; and then their merit assists us in the avodah of Hashem, to save us in galus and to merit the geulah, speedily in our days.

The zechus avos is not automatic — we activate it by actively choosing to follow in the forefathers' path. When we daven to "the God of Avraham," we are declaring our wish to receive Hashem's sovereignty in the very channels the Avos opened. That choice draws their merit down to aid our own avodah, protect us in galus, and bring the geulah.

Summary: Avraham Avinu was the living hachanah for both galus and geulah; his merit is what sustains Bnei Yisrael through every exile and makes them worthy of redemption. By consciously choosing the ways of the Avos and accepting Hashem's sovereignty as they did, we activate that zechus avos to support our avodah, protect us in galus, and hasten the geulah.