"they shall see the Son of man coming in the clouds of heaven with power and great glory…This generation shall not pass, till all these things be fulfilled."
Mt 24:30, 34
"…when he cometh in the glory of his Father with the holy angels....there are some of those standing here, who in no wise shall taste of death, until they see the kingdom of God having come in power. "
Mk 8:38
"... when he shall come in his own glory, and in his Father's, and of the holy angels…there are some of those standing here, who in no wise shall taste of death, until they have seen the kingdom of God. "
Lk 9:26-27
"But in those days, after that tribulation, the sun shall be darkened, and the moon shall not give her light, And the stars of heaven shall fall, and the powers that are in heaven shall be shaken…this generation shall not pass, till all these things be done. "
Mk 13:24, 25, 30
"For these be the days of vengeance, that all things which are written may be fulfilled… for the powers of heaven shall be shaken… This generation shall not pass away, till all be fulfilled. "
Lk 21:22, 26, 32
"...Hereafter shall ye see the Son of man sitting on the right hand of power, and coming in the clouds of heaven. "
Mt 26:64
"Then said he to the multitude..O generation of vipers, who hath warned you to flee from the wrath about to come? And now also the axe is laid…every tree therefore which bringeth not forth good fruit is hewn down, and cast into the fire."
Lk 3:7-9
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And many others. There is nothing in the Bible indicating that it should happen later than in their generation.