An Example of the "Agent Principle" in the Bible: Elisha fulfilling Commandments Elijah was Tasked with

In the Bible, there are a number of examples of an agent fulfilling prophecies/commandments that were originally said would be fulfilled by another can be seen in the Elijah/Elisha narrative. As John Tvedtnes noted:

 

For example, the Lord commanded Elijah to anoint Hazael king of Assyria and Jehu king of Israel and Elisha as prophet in his stead (1 Kings 19:15-16). Elijah did, indeed, call Elisha (1 Kings 19:19-21). But it was Elisha, after Elijah was taken to heaven, who sent one of the prophets to anoint Jehu (2 Kings 9:1-10), and Elisha himself announced to Hazael that he would be king (2 Kings 8:7-13). In other words, Elijah did not accomplish two of the three tasks assigned to him by God. Does this make him a false prophet? In the LDS view, he did the right thing by designating his successor, who followed through on unfinished business. In the same manner, some of the things the Lord commanded the early Latter-day Saints to accomplish (such as to settle in Zion, Missouri) will be fulfilled by their descendants and successors. Likewise, the blessings pronounced on each of the tribes of Israel by Jacob (Genesis 48-49) and Moses (Deuteronomy 33) are to be understood as blessings for their future generations, not only for the men to whom the words were addressed. (The Nature of Prophets and Prophecy)

 

I will note that if this were to happen within an LDS context (e.g., Brigham Young fulfilling prophecies that the D&C said would be fulfilled by Joseph Smith), Evangelicals would use such as "proof" Joseph was a false prophet. The reason is that no matter the evidence in support for LDS truth claims, whether it be the biblical evidence for LDS theology, evidence for Book of Mormon and Book of Abraham historicity, etc., they labour under the a priori assumption Mormonism must be false, so not only do they reject anything in favour of the LDS Church, they are so blinded by their bias that they engage in blatant double-standards.