I agree that there is an OT-allusion to Isa 50:6.
But I assume that an expectable objection could be the following: According to such literary interpretations, the word “prophesy” has only the function of a literary device that makes sense in the relationship between author and reader, but not at the level of the narrative. It assumes from the outset that the word has almost no meaning on the lips of the acting persons in Mark's account and gives no answer to the question of why the persons in GMark are saying “prophesy” to Jesus. The interpretation of Dean B. Deppe ("The Theological Intentions of Mark's Literary Devices") seems to me to be typical of current Markan scholarship.
I believe this is the reason why many (most?) readers still prefer the “unmistakably clear picture“ of Luke to interpret also Mark's and Matthew's accounts, at least in the sense as abbreviated versions of an original story that is better preserved in Luke.
It seems to me that there are a growing number of scholars (nevertheless a minority) who assume that the word “prophesy” has a different intended meaning in GMark as in GLuke. However, I would not rule out the possibility that the word could have a different meaning in GMatthew too.
I would argue that for two reasons: The traditional meaning of the verb "prophesy!" and the normal use of the Greek word for „smote“ in the KJV (παίσας – paisas).
In Luke's version „the men that held Jesus“ play a guessing game with him so that he may use his second sight to declare which of them hit him right now. But such a understanding has nothing to do with the traditional meaning of the word „prophecy“.Luke 22:64 … and asked him, saying, Prophesy, who is it that smote (παίσας – paisas) thee?
I think that against the biblical background, the word „prophecy“ means to get a revelation or a message from God and the instruction to declare it to the people to prepare them in a current situation or for a future situation or to foretell important events of the future. From 1 Corinthians and the Didache we may get the impression that in NT times there were also minor prophecies, but clearly not in the kind of Luke's guessing game. In contrast, in Mark's account the word "prophesy!" occurs in the context of real prophecies as the temple destruction and the coming of the son of man, exactly what one would expect when the word "prophecy" is at stake. Therefore I tend to think that the word "prophesy!" is an alien in Luke's account.
The same applies to the word „smote“ (παίσας – paisas), an inflection of παίω (paió). If I have not overlooked something the normal use of this Greek word express always a little bit the result and not just the action itself. It means bring down by beating, wound by beating, punish by beating, humiliate by beating etcetera. It can be used for a single hit, but that would be a knockdown or a blow that inflicts a wound. It can be used for many hits, but then it refers to the whole process. In its normal use it makes no good sense in a question that distinguishes between different hits as alternatives to choice ("Which of us smote you?")
I think if you weigh these points then there could be the possibility that Matthew meant
as a rhetorical question with the intended answer that Jesus may recognize that it is God himself that brought him down. (There are few of such rhetorical questions in the synoptic gospels, the most famous may be Mark 4:41 “Who then is this, that even the wind and the sea obey him?”)„Prophesy unto us, thou Christ, Who is he that smote thee?“