"Yigal, son of Yaakov, will rejoice Israel. Yigal, son of Avraham, is not written here, only Yaakov. Why is it that Yaakov is happier than all the other patriarchs? Rabbi Shimon ben Lakish said that when Israel sins, Yaakov feels it from the Cave of Machpelah, as it is written (Hoshea 5:3), "For now, O Ephraim, you have committed harlotry; Israel is defiled."
And so, when joy comes to Israel, Yaakov is happier than all the other patriarchs because he is prepared for the feast, as it is said (Isaiah 48:12), "Hearken unto me, O Jacob and Israel, My called; I am He; I am the first, I also am the last." What does it mean, "My called"? It means those who are prepared for the feast, as it says (I Samuel 9:22), "And he gave them a place at the head of the called ones."
And Rav said that it is like a father who marries off his daughter. Who is happy? Only the father of the bride, as it says (Isaiah 29:22), "Therefore, thus says the Lord unto the house of Jacob, who redeemed Abraham." So you can say that when redemption comes to Israel, Yaakov is happier than all the other patriarchs. That is why it says, "Yigal Yaakov Yismach Yisrael" (Yaakov will rejoice and Israel will be glad)."