Musar su Zaccaria 9:78

ויהי לי שור וחמור . This statement has to be understood at face value when it was addressed to Esau in line with Rashi's explanation that, whereas in Isaac's blessing Jacob was promised "dew from the heavens and the fat parts of the earth," i.e. success as a farmer, he had in fact only acquired herds. Esau had no reason to be jealous, since that part of Isaac's blessing had not been fulfilled. The same words put in the mouth of Jacob's spiritual emissaries convey a different meaning, however. These words allude to a number of merits Jacob had acquired and that would accrue to him in the future. They correspond very much to Bereshit Rabbah 75,6 which explains that the word שור refers to the כהן משוח מלחמה, the priest who accompanied the troops into battle (Deut. 20,2). The Midrash bases this on Moses' blessing to the tribe of Joseph in Deut. 33, 17: בכור שורו הדר לו, "His firstling bullock, majesty is his." The word חמור is understood as a reference to the Messiah who traditionally is perceived as riding on a donkey, based on Zachariah 9, 9: עני ורוכב על החמור. The צאן, flock, that Jacob also mentions refers to the people of Israel who are repeatedly called צאני"My flock," by G–d in Ezekiel 34. The words עבד ושפחה also refer to Israel as the latter are alluded to in that manner in Psalms 123, 2.