Commenting on the confrontation between Yehuda and Yosef narrated in the beginning of Parashat Vayigash, the Midrash Tanchuma relates:
At the time when Yehuda and Yosef were quarreling with one another, the ministering angels said to each other: Let us go down and see the ox and lion wrestling with one another. Normally, the ox is fearful of the lion, but now, the ox and lion continue to wrestle, and there is jealousy between them until Mashiach comes.
Why are Yehuda and Yosef depicted as a "lion" and "ox," and why is this struggle destined to continue until the Messianic era?
Rav Yeshaya Eherenfeld (son-in-law of the Chatam Sofer), in his work Shevet Sofer, suggests that the Midrash here portrays the tension between Yosef and Yehuda, and between their descendants, as symbolic of the age-old struggle between inherited and acquired authority. The lion is, by nature, the unchallenged "king" of the animal world, and thus represents the tribe of Yehuda, which was granted royal authority – "The scepter shall not depart from Yehuda" (Bereishit 49:10). Yehuda, like the lion, is granted royal authority through a kind of "natural law." The ox, Rav Ehrenfeld explains, symbolizes authority obtained through talent and skill. The vital agricultural work performed by oxen in ancient times renders it the "king" of domesticated animals, as it is the most valuable human asset among all animals. The ox thus symbolizes prestige and honor achieved through hard, dedicated work and skillful talents. Yosef, like the ox, eclipsed his brothers in terms of acumen and skill, and thus posed a challenge to Yehuda's "natural" status of leadership.
The conflict historically waged between the tribes of Yehuda and Yosef epitomized this struggle between these two models of royal authority. Yerovam, a descendant of Yosef, challenged the presumed royal status of the Davidic dynasty, asserting himself as a most suitable candidate for kingship. The roots of this conflict, as mentioned, can be found already in the struggle between Yosef and his brothers. Yehuda was named king of the tribes, but Yosef displayed extraordinary skill and talent on the basis of which he sought to assert his leadership.
The Midrash Tanchuma cites in this context the verse in Sefer Yeshayahu (11:13), "The envy of Efrayim shall be eliminated; Efrayim will not feel envious of Yehuda, and Yehuda will not oppress Efrayim." The prophet foresees the time when a resolution will be found for this age-old conflict, when the kings of Yehuda will rule effectively and succeed in establishing their authority, while the talents of Efrayim will be harnessed towards the nation's advancement in other areas. The "lion" will retain its unchallenged position as king, while the "ox" will continue to serve its vital role in furthering Am Yisrael's interests and goals.