Rashi explains that each part of the pasuk refers to the opening berocha of the amida prayer. (The first berocha of the Shemone Esrei corresponds to each of the three Avos and concludes with Mogen Avrohom – “Shield of Avrohom”.)
“And I shall make you into a mighty nation” – corresponds to “the G-d of Avrohom”.
“And bless you” – corresponds to “the G-d of Yitzchok”.
“And make your name renowned” – corresponds to “the G-d of Yaakov”.
We might have assumed that we would include all the Avos in the berocha’s conclusion, but the pasuk says: “and you shall be a blessing”; we conclude with you [Avrohom] and not with them.
The holy Apta Rav, mechaber of Ohev Yisrael, explained that each of the Avos HaKedoshim exemplified one of the three pillars upon which the world stands: Torah, Avoda and Gemilus Chassodim – Torah study, service of Hashem, and acts of loving-kindness. Avrohom represents Gemilus Chassodim, since we find him performing acts of loving-kindness, such as having a tent open to all four directions for travelers and guests, running an eishel – an inn, for achila, shesiya and lina – food, water and lodgings, as well as feeding the three guests who came to him after his bris. Yitzchok represents Avoda, since he was offered on the mizbe’ach. Yaakov represents Torah (Bereishis 25:27), a tom who dwelt in tents, which Rashi explains refers to the Yeshiva of Shem and Ever.
We can thus explain the words of our sages (as cited above by Rashi) based on the three pillars that we ascribe to the Avos. Can it be that we conclude with all of them? Must we fulfill all three pillars? We conclude with Avrohom and his corresponding pillar of acts of loving-kindness. This, explains the Apta Rav, means that it is sufficient to fulfill Avrohom’s attribute of Gemilus Chassodim. (Based on the handwritten manuscript of the Maharil of Kolomaya from Tzefas)
