I have blogged before about David Daube’s observation that many of the Bible’s mountaintop scenes are instances of the legal device called “traditio”: when conveying a purchased object into the possession of its new owner, one usually just hands it over (Lat. trado). But for some possessions, this is physically impossible. Accordingly, inspection of a property may be used as the formal means of traditing it into the ownership of another. This is done in the case of Abram in Genesis 13:17: “Arise, walk in the land through its length and its width, for I give it to you.” (Genesis 13:17 NKJV)
Similar to this is, Moses’ mountaintop viewing of the promised land in Deuteronomy 32:49: “Go up this mountain of the Abarim, Mount Nebo, which is in the land of Moab, across from Jericho; view the land of Canaan, which I give to the children of Israel as a possession..” (Deuteronomy 32:49 NKJV)
Daube points out Satan’s attempted, but failed, use of the same convention in Matthew 4:8, where he tries to get Jesus to make a deal, offering the kingdoms of the world in exchange for worship. Again, this is on “an exceedingly high mountain”.
I would now like to add another instance: the Great Commission too takes place on a mountain, and this setting seems significant, especially in light of Jesus’ prior declaration that all authority has been given to Him. This is a pointed contrast with Satan’s statement that “All this authority I will give You, and their glory; for this has been delivered to me, and I give it to whomever I wish.” (Luke 4:6 NKJV) Having won authority over the world, Jesus now bestows the kingdom on His disciples. As NT Wright puts it,
“Israel was to be the people who inherited YHWH’s sovereign rule over the world. The promised land was a sign of this, but already by the first century many Jews had glimpsed the possibility, already implicit within the Adam–Abraham nexus, that the land was simply an advance signpost to YHWH’s claim over the whole of creation.” — Wright, Paul and the Faithfulness of God
That’s why the Great Commission is on a mountain: it is the fulfillment of Genesis 13, Deuteronomy 32, and Matthew 4.