Mark 9:1
And he said to them, truly I tell you, some who are standing here will not taste death before they see that the kingdom of God has come with power — the saying immediately follows the shame/Son of Man saying of 8:38, creating a sequence: first the shame of the cross, then the power of the kingdom's arrival. Some who are standing here will not taste death before they see — the timeframe is within the generation of the disciples. The kingdom coming with power is fulfilled variously by the transfiguration (six days later), the resurrection, Pentecost, and the spread of the gospel through the Roman Empire within a generation.