May The Lord Make you as Ephraim and as Menashe

This week's portion, Vayechi, describes Ya'akov's blessing to Ephraim and Menashe, which was adopted as a blessing for sons for posterity. Why was this specific bracha chosen? Why not, for instance "May the Lord make you as Avraham, Yitzchak and Ya'akov", the patriarchs of the nation? The question intensifies when we recall that daughters are blessed with the names of our matriarchs Sarah, Rivkah, Rachel and Leah!

A wonderful explanation appears several times in the writings of R' Tzvi Elimelech of Dinov, author of the "B'nei Yissachar":[1]

"And Ya'akov Avinu, when he placed Ephraim before Menashe, saw that Ephraim did not become prideful because of his elevated position, quite the opposite…and that Menashe was not jealous. Therefore he blessed them: 'By thee shall Israel bless' …as Ephraim, with no conceit, and as Menashe with no jealousy of his brother's favor".

Let us expand on this theme. Ephraim and Menashe are unique in their complete absence of rivalry and jealousy. Throughout the book of Bereshit we find various cases of quarrels between brothers:
Cain and Abel – a dispute culminating in murder!
Yitzchak and Yishma'el
Ya'akov and Esau
Yosef and his brothers

In Bereshit, Ephraim and Menashe are an example of the only case of brothers who are not bitter opponents. Instead, they are a living example of brothers who live in harmony.