הָאַ֥יִל אֲשֶׁר־רָאִ֖יתָ בַּ֣עַל הַקְּרָנָ֑יִם מַלְכֵ֖י מָדַ֥י וּפָרָֽס׃
Ang lalaking tupa na nakita mo na may dalawang sungay, ang mga iyon ay ang mga hari ng Media at Persia.
Ezra ben Solomon
I have written all of this because I have seen an interpretation in Genesis Rabbah in which the three-year old goat is correlated with the kingdom of Greece, with the two-horned ram appearing in Daniel [8:3] brought as corroborating evidence. This seems to me to be either a mistake or a case of scribal error, for it is clearly stated in Daniel that the two-horned ram represents the kings of Medea and Persia.
Rabbeinu Bahya
ואת הצפור לא בתר , “and he had not cut the bird in half.” The reason Avram had cut up the four-legged animals but not the birds was that the former represent the idolatrous Gentile Nations, and these have been compared to animals as it says (Psalms 22,13) סבבוני פרים רבים, “many bulls surround me.” It is also written in Daniel 8,20 האיל אשר ראית, “the ram that you saw ....are the kings of Medes and Persia.” In verse 21 of the same chapter the king of Greece is described as הצפיר השעיר, the “he-goat.” On the other hand, in Song of Songs 5,2 and 2,14 the Jewish people are compared to doves. Seeing that Israel will continue to exist indefinitely, Avram did not cut up the birds representing it.
Rashi
ואת הצפור לא בתר BUT THE BIRDS SPLIT HE NOT — Because other nations are compared to bulls, rams and goats, as it is said (Psalms 22:13) “Many bulls have encompassed me”, and it says, (Daniel 8:20) “The ram which thou sawest having two horns, they are the kings of Media and Persia” and it further says, (Daniel 8:21) “And the rough he-goat is the king of Greece” — and Israel is compared to young doves, as it is written, (Song 2:14) ‘‘O my dove that art in the clefts of the rock” — he therefore divided the animals indicating that other nations will gradually perish, ואת הצפור לא בתר but “the birds split he not”, suggesting thereby that Israel will live forever (Pirkei D'Rabbi Eliezer 28).