‘And seeing the crowds, he went up into the mountain, and when he had sat down, his disciples came to him, and he opened his mouth and taught them, saying,'
Jesus had seen many crowds, and had welcomed them, but at this point in time He considered that they were preventing Him from teaching His disciples more specifically. So He went up into the mountain to get away from the crowds. The description is deliberately separating this teaching off from that to the crowds.
The definite article on ‘the mountain' may simply indicate ‘the mountain nearby', or it may indicate a favourite mountain which He used regularly. Or it may even convey the idea of a place for special seekers after God, just as today after a time of prayer we might say that we have been ‘on the mountain top'. The quieter atmosphere and surrounding grandeur would certainly enable His disciples to listen better. But there is no attempt to associate it with anything in the Old Testament Scriptures. Matthew is not here overtly trying to present Jesus as a new Moses. Rather he is seeing Him simply as attempting to get the disciples somewhere where they can be brought closer to God, just as He had previously sought out a mountain when he was working out His future.
Note On The Mountain.
It is probable that the mention of ‘the mountain' is to be seen as significant in Matthew. Mountains in Matthew can be divided into three groups, mention of a ‘high (or very high) mountain', mention of ‘the mountain', and general mentions of mountains, including the Mount of Olives.
1). References to a high mountain.
There is one reference to ‘a very high mountain' and one to ‘a high mountain'. The former was probably an ideal mountain, and the second literally one that really was unusually high. But both are places where Jesus had extreme experiences. Let us briefly consider them:
‘Again, the Devil takes him up into a very high mountain, and shows him all the kingdoms of the world, and the glory of them' (Matthew 4:8).
‘And after six days Jesus takes Peter, James, and John his brother, and brings them up into a high mountain apart' (Matthew 17:1), and there He is transfigured before them.
It will immediately be obvious that these are two ‘out of this world' experiences. In the one the Devil is trying to draw Him into his clutches, in the other He is surrounded by God's glory as His own glory is revealed (compare John 1:14; John 17:5). It may well therefore be that in these cases the height of the mountain was also to be seen as symbolic, as well as in one case literal.
2). References to ‘The Mountain'.
It may well be that when Matthew indicates that Jesus went up into ‘the mountain' he wants us to know that He has an important message to convey, for each example contains an event of significance.
a ‘And seeing the crowds, He went up into the mountain, and when He was sat down, His disciples came to Him' - (for discipleship instruction - Matthew 5:1). When He was come down from the mountain, great crowds again followed him (Matthew 8:1).
b ‘And after He had sent the crowds away, He went up into the mountain apart to pray, and when the evening was come, He was there alone' (Matthew 14:23), after which he walked on water as a demonstration of His power over creation, and over nature. By this He makes clear that He is not only the Lord of the land, but is also the Lord of the sea, a sea of whose power His disciples were well aware. His people had good cause to remember His power over the sea (Exodus 15:8; Exodus 15:10; Exodus 15:19) and the sea was always an unknown force, the control of which by God was looked on with awe in the Psalms (Psalms 74:13; Psalms 77:19; Psalms 89:9). And the result is that they worshipped and said, ‘Truly You are the Son of God' (Matthew 14:33).
b ‘And Jesus departed from there, and came near to the sea of Galilee, and went up into the mountain, and sat down there' (Matthew 15:29). And there the crowds came to Him and He performed miracles and fed four thousand men along with women and children at a covenant meal. ‘And they glorified the God of Israel' (Matthew 15:31).
a ‘And the eleven disciples went away into Galilee, into the mountain where Jesus had appointed them' (Matthew 28:16). And there He appeared to them and gave them their commission to make disciples of all nations and promised His continuing presence with them.
It will be noted that in the first two cases the mountain is seen as a kind of haven from the crowds. In the third case it does not at first appear to be a haven from the crowds, but we should note that this is a special crowd. They are all included in the partaking of the covenant meal and have been with Him in that isolated place listening to His words for three days. They are therefore almost if not completely disciples, and not just the normal ‘crowds'. The fourth case fits into the pattern of the other three. It is where He meets with His disciples to give them their commission for the future.
Furthermore the first and the last examples are places where Jesus specifically charges the disciples with their responsibilities, while the two middle ones reveal His power over creation, and end with the glorifying, in the one case of Jesus, and in the other of the God of Israel. We are probable therefore justified in seeing mention of ‘the mountain' as pointing to ‘mountain top' experiences.
End of Note.
And there ‘He sat down' and His disciples ‘came to Him'. His sitting down suggests that their coming had been anticipated. It was normal for a Jewish Teacher to teach His disciples sitting down. And once they were there He ‘opened His mouth' (compare Matthew 13:35 citing Psalms 78:2). The idea behind this phrase would seem to be that of indicating something new that would be spoken (compare Ezekiel 3:27; Daniel 10:16). Then after that ‘He taught them'. We note therefore the careful preparations made to get everything right for the delivery of what He was about to say. He clearly considered it to be very important.