For the sake of rounding out the Biblical picture, it’s worth noting what Mark presents in association with the fig tree and the mountain. Mark reports Jesus as saying “Whenever you stand praying, if you have anything against anyone, forgive him, so that you Father in heaven will also forgive your sins” (11:25). In contrast, and though clearly utilizing the Markan narrative to provide the basis for his own, Luke omits any mention of the fig tree or mountain, moving directly to Jesus return to the Temple courts and the challenge to Jesus’ authority that comes from the temple authorities.
Though this study will not spill a great deal of ink with conjecture on why Matthew and Mark include the story of the withered fig tree whereas Luke does not, one could surmise that the appearances of the fig tree in the Matthean and Markan narratives, with both (Matthew most likely relying on Mark) connecting the withered fig tree with the mountain to be removed, could possibly have some bearing on the conclusions to be drawn. Perhaps its appearance and correspondence to the mountain that is in view (the Temple mount, so it is both literal and metaphorical) is somehow linked to Jesus’ insistence that no man knows the day or the hour, which, as has been pointed out, is to be found in Matthew and Mark, but not in Luke. Certainly, the fig tree did not expect to wither on that day and at that moment---it clearly did not know the hour.
In addition, it is necessary to acknowledge and report the divergence in the Gospel stories surrounding Jesus’ triumphal entry. An honest observer does not simply ignore these things and pretend that they are not there, though it is also quite possible to insist that differences in detail do not derail from the overall message of the accounts nor do the differences really present much cause for concern, primarily because the authors (and that world in general) did not operate with the strict, modern, western notions in regards to “doing history”. Fluidity in reports were acceptable, as long as the major details remained intact, especially when any glaring problems could and would be corrected by the oral/aural community, which was often a far better guardian of stories in that day than was the written word.
That said, Matthew’s account has already been detailed here quite well. Owing to the fact that Mark is believed to be foundational for Matthew and Luke’s account, it must be said that it is Matthew’s account that is divergent, rather than Mark’s. The divergences are accounted for by each author having slightly different goals for the telling of the Jesus story as received by their target audiences in the growing Jesus community that they want to achieve through the delivery of their accounts. So even though each has the goal of setting forth the story of Jesus, each comes at it from a slightly different angle, which is perfectly understandable. Honestly, it needs to be said that if each told the story in the same way, the world would have no need for multiple Gospels, and Christendom and the world at large would lack the rich and manifold witness to Jesus provided by these evangelists---not to mention their diverse perspectives and portrayals of Jesus that serve to provide a more complete sense and picture of the one that so many call Lord.
What are those divergences? For Mark, Jesus does head to the Temple upon the occasion of His triumphal entry into Jerusalem. However, Mark does not record Him immediately engaging with the buyers, sellers, and money changers, nor making His Jeremiah-esque stand. In Mark’s telling, this takes place on the following day, which is also the day that Jesus speaks to the fig tree while on His way to Jerusalem. However, in Mark’s presentation of that detail, and even though the fig tree may indeed have immediately withered, the disciples do not comment on this withering until the following day, which is when Jesus offers up His commentary concerning the fig tree, the mountain, and the need to offer forgiveness.