So he blessed them that day, saying, “By you shall Yisrael invoke blessings, saying: Hashem make you like Efraim and Menashe.” Thus he put Efraim before Menashe.
Genesis 48:20 (The Israel Bible™)

וַיְבָרֲכֵם בַּיּוֹם הַהוּא לֵאמוֹר בְּךָ יְבָרֵךְ יִשְׂרָאֵל לֵאמֹר יְשִׂמְךָ אֱלֹהִים כְּאֶפְרַיִם וְכִמְנַשֶּׁה וַיָּשֶׂם אֶת־אֶפְרַיִם לִפְנֵי מְנַשֶּׁה
Hear the verse in Hebrew

vai-VA-r’-KHAYM ba-YOM ha-HU lay-MOR b’-KHA y’-va-RAYKH yis-ra-AYL lay-MOR
y’-sim-KHA e-lo-HEEM k’-ef-RA-yim v’-khim-na-SHEH va-YA-sem et ef-RA-yim lif-NAY
m’-na-SHEH

The Blessing of the Sons

Derived from the above verse, to this day Jewish parents bless their sons each Shabbat(Sabbath) with the words, "May Hashem (God) make you like Efraim and Menashe." What is so unique about this pair of Biblical brothers? The two sons of Yosef (Joseph) played a significant role in the formation of the Jewish People. They were the first of Avraham's (Abraham's) family to be born in Egypt. Despite their physical distance from the Land of Israel, they remained loyal to the traditions of their ancestors. Efraim and Menashe, therefore, represent the key to the survival of the Jewish People and their return to Israel. For this reason, these brothers were chosen as special role models for the Children of Israel.

Learn more about the blessing of the sons