Hi Oatmeal,
Mat 5:1 But, seeing the multitudes, He went up into a mountain,—and, when He had taken a seat, His disciples came unto Him;
Looking at this Scripture we see Jesus saw the multitudes 'then' He "went up into a mountain" and it is there that the disciples came to Him. I believe the multitude was gathered below and up on the mountain He was separated from the multitude and with only His disciples.
Then later in verse 28 you will see He was with the multitude again, obviously He had gone back down the mountain to the multitude.
Mat 7:28 And it came to pass, when Jesus ended these words, with astonishment were the multitudes being struck at His teaching;
Now we also have Luke's version of this same sermon with the disciples and the multitude. Here I think it may show Jesus wasn't speaking to them at the same time. It starts out with Jesus calling all His disciples together and choosing out the 12. This seems to be the match to Matt. 5:1.
Luke 6:13 And, when it became day, He called His disciples, and chose from them, twelve, whom also he named, Apostles,—
I think verse 13 is when Jesus was up on the mountain with the disciples, then it shows that He came down off the mountain in verse 17, back to where the multitude was.
Luke 6:17 and, coming down with them (disciples), He stood upon a level place, also a great multitude of His disciples,—and a great throng of the people, from all Judaea and Jerusalem and the sea-coast of Tyre and Zidon, who had come to hearken unto Him and to be healed from their diseases;
But when we go down to verse 20, this is referring back to when He is speaking to the disciples, as He says so.
Luke 6:20 And, He, lifting up His eyes towards His disciples, was saying:—Happy, ye destitute, for, yours, is the kingdom of God.
Luke 6:39 He spake, moreover, a parable also, unto them: Can, the blind, guide, the blind? will not, both, fall into, a ditch?
But then when you come down to verse 39 and this is when He starts to speak to the multitude as it says in "a parable" He spoke to "them." He always spoke to the people/multitude in parables.
Mat 13:34 All these things Jesus spoke to the multitude in parables; and without a parable He did not speak to them.
So in Matt. there is no division between what He said up on the mountain and when He came down and spoke to the great multitude. But in Luke it seems more like it was maybe a two part thing, one for the disciples and one for the multitude.
mercy, peace, and love
Kat