Tosefta zu Könige I 1:33

A Sage takes precedence over the King of Israel. [If] a Sage dies, we have no one like him, but if the King of Israel dies, all of Israel is fit for kingship. The King takes precedence over the High Priest, as it is said (I Kings 1:33), "And the King (i.e., King David) said to them (i.e., the Zadok the High Priest, among others), 'Take with you the servants of your lord (referring to himself), and have Solomon my son ride on my mule." The High Priest has precedence over a prophet, as it is said (I Kings 1:34), "And let Zadok the [High] Priest and Nathan the Prophet anoint him (i.e., Solomon) there" -- Zadok was mentioned before Nathan. And it says (Zech. 3:8), "Hear now, Yehoshua the High Priest, you and your fellows (i.e., fellow priests) that sit before you. [For these are men of portent (mofet), that I will bring forth a shoot from My servant]." Can these be ordinary men? Thus, the Torah states that "these are men of portent," and there is no "portent" but a prophet, as it is said (Deut. 13:2, referring to a prophet): "And if he gave to you a sign or a portent (mofet)."

A horse may not be tied to a mule, or a mule to a donkey, or a donkey to a wild ass, because this one may be driven with that one. If he [nonetheless] did so, Rabbi Meir holds him liable, and the Sages exempt him. Rabbi Yehuda says, the offspring of a female horse and the offspring of a female donkey are forbidden [to be tied] together, but the sages say, all mules are a single species. Assi the Babylonian says, it is forbidden to ride on the back of a mule, from a kol v'chomer: Just as where it is permitted to wear two cloaks on top of one another [even if one is made of wool and the other of linen], yet it is forbidden [to wear a single cloak] if it is of a forbidden mixture, thus where it is forbidden to drive two [diverse species] together, does it not all the more so stand to reason that a forbidden mixture of both them should be forbidden? They said to him, behold, it says (1 Kings 1:33, JPS tr.), "and have my son Solomon ride on my mule, and bring him down to Gihon." He said to them, one cannot derive [halacha] from [actions performed] in urgency. They said to him, it says [as to Solomon] (2 Kings 18:3), "He did what was correct in the eyes of God, like all that his father David had done, and [as to David] (1 Kings 15:5), "He never turned throughout his life from all that had been commanded him [except in the matter of Uriah the Hittite]."