(יב לב) "אתו אנכי ירא כי עשו מיד אחי מיד נא הצילני"
Harav Nosson Nuta Shapiro, the Megaleh Amukos, explained:
"נא מיד אחי– is an acronym for amen, and Yaakov had in mind in his tefillah that the merit of answering amen should advocate for him that his tefillah should be accepted and he should be spared from his brother Eisav. "Indeed, this merit of amen was effective for him, as he saw face to face the angel of Eisav and was saved."
Megaleh Amukos
The segulah of answering amen as a salvation and to have the tefillah accepted is brought in the holy Zohar (Vayeilech 285b), and he writes, based on the commentary of the Sulam there: "When Am Yisrael on this world are careful to answer amen and to concentrate the way they have to...then when they are harassed, they pray their tefillah to their Master, and the Voice declares in all the worlds: ‘Pischu she'arim veyavo goy tzaddik shomer emunim' (Yeshayahu 26:2). Do not read it ‘emunim' but rather ‘amenim,' meaning that they are careful to answer amen. Just like Yisrael opened for them the gates of brachos, now as well open the gates, and their tefillos against those who harass them will be accepted."
The Tana Devei Eliyahu (Rabbah 11) similarly explains the passuk in Shiras Devorah (Shoftim בפרע פרעות" :)5:2 – "'בישראל בהתנדב עם ברכו ה
What did Devorah prophesize to Am Yisrael? She told them: With whom does HaKadosh Baruch Hu take revenge for Am Yisrael on the nations of the world? With the people who go to shul morning and evening and answer amen and bless HaKadosh Baruch Hu with amen...Of them the passuk says (Tehillim 55:19): ‘פדה "'.בשלום נפשי מקרב לי כי ברבים היו עמדי
