John Gill Commentary Mark 9:1

"And he said unto them, Verily I say unto you, There are some here of them that stand [by], who shall in no wise taste of death, till they see the kingdom of God come with power." — Mark 9:1 (ASV)

And he said to them
Both to his disciples, and the multitude,

truly I say to you, there are some of them that stand here ;
that were then living, and upon the spot,

which shall not taste of death ,
or die,

till they have seen the kingdom of God come with power .
When Jesus was declared both Lord and Christ, by the wonderful effusion of the Holy Spirit; the Gospel spread in the world both among Jews and Gentiles, in spite of all opposition, under the power and influence of the grace of God, to the conversion of thousands of souls; and that branch of Christ's regal power exerted in the destruction of the Jewish nation; (See Gill on Matthew 16:28). This verse properly belongs to the foregoing chapter, to which it is placed in the Vulgate Latin version; and so it concludes one in Matthew, and ought not to begin a new chapter.