וְהִנֵּ֣ה מִן־הַיְאֹ֗ר עֹלֹת֙ שֶׁ֣בַע פָּר֔וֹת יְפ֥וֹת מַרְאֶ֖ה וּבְרִיאֹ֣ת בָּשָׂ֑ר וַתִּרְעֶ֖ינָה בָּאָֽחוּ׃
И вот, вышли из реки семь коров, благодатных и толстых; и они питались тростниковой травой.
Noam Elimelekh
----“When out of the Nile there came up seven cows.” We can say that the verse is hinting at great things, given that Joseph also had two dreams, the first of the wheat and the second of the sun and moon. Joseph is identified with the s’firah of y’sod, foundation, which is the Tsaddik, whose desire is always to draw to Israel the abundance which it deserves according to God’s will. Thus the first dream is about wheat, to draw mercy to Israel so that its material well-being will be available in ample amounts. Only afterwards do we see what the Tsaddik accomplishes in the supernal worlds, alluded to in the sun, moon, and eleven starsHere also, Pharaoh dreamed two dreams on these same two levels. The nations received sustenance by means of the bulls which Israel sacrificed and Pharaoh saw cows because he was from the feminine side. And it is known that seven hints at the seven days of creation. So the seven healthy cows refer to the nations which live quietly and in peace, while the seven poor-looking cows refer to Israel, impoverished and persecuted in this bitter exile.
Sefat Emet
Concerning the dream: "Seven cows, fair of appearance, etc., and they were grazing in the achu." And in the Midrash: "Achvah (brotherhood) and peace in the world" - see there. The allusion is to the aspect of Joseph, who is peace, and he is the aspect of Shabbat, which encompasses the six days in a unity of oneness. Therefore he elevates everything to the root. This is what is said concerning Joseph: "A son of seventeen years, he was shepherding et achav (his brothers)." But concerning the [other] tribes it is written "to shepherd the flock," and the Sages expounded: et is dotted to [teach] "to shepherd themselves" - that they were not in proper unity, for they are the aspect of particularity. Similarly, the abundance that comes during the days of action - each day is unto itself. Therefore the allusion was from the seven cows that came after them, which were not in achvah (brotherhood/unity). But concerning Joseph it is written et achav (his brothers). Therefore it alludes to "seventeen." The explanation is: the seven have unification in the first three [sefirot], for so is Shabbat - the light of the seven days. In truth, Shabbat prepares the abundance also for the days of action, as it says "from it all six days are blessed." But it is not in revelation, as it is said that the manna did not fall on Shabbat. On the contrary, the weekdays prepare for Shabbat. This is the allusion: "And it was not known that they had come into their midst." But in truth, Shabbat sustains all the days. This is what is said concerning Joseph: "Fair of form and fair of appearance" - that the righteous one is "good of eye" (tov ayin), and through him all are blessed.