Did Jesus say that he was coming back within a generation? It seems that Jesus was admitting that he would return after the destruction of the temple in 70 A.D.
That the abomination of desolation was the Roman leader Titus.
14 “But when you see the abomination of desolation[w] standing where it[x] should not be” (let the reader understand),[y] “then those in Judea must flee[z] to the mountains. 15 The one on the roof[aa] must not come down or go inside to take anything out of his house.[ab] 16 The one in the field must not turn back to get his cloak. 17 Woe to those who are pregnant and to those who are nursing their babies in those days! 18 Pray that it may not be in winter. (Mark 13:14-18 NET)
Jesus then says that after this happens he will come back.
“But in those days, after that suffering,[ai] the sun will be darkened and the moon will not give its light... Then everyone[ak] will see the Son of Man arriving in the clouds[al] with great power and glory. 27 Then he will send angels and they will gather his elect from the four winds, from the ends of the earth to the ends of heaven.´(Mark 13:24,27 NET).
I interpret Matthew 24 from an amillennialist point of view.
Matthew chapter 24 is a complex chapter because at the beginning of the chapter the disciples ask a lot of questions all together.  It looks as if they might be thinking the Temple will be destroyed at the end of the age:-

And Jesus went out, and departed from the temple: and his disciples came to him for to shew him the buildings of the temple.  And Jesus said unto them, See ye not all these things? verily I say unto you, There shall not be left here one stone upon another, that shall not be thrown down.  And as he sat upon the mount of Olives, the disciples came unto him privately, saying, Tell us, when shall these things be? and what shall be the sign of thy coming, and of the end of the world?  (Matthew 24:1-3)

Part of our Saviour's answer relates to the time of the destruction of the Temple and part of it relates to the time of the end of the age. A key section for understanding the chapter is verses 33-36:

So likewise ye, when ye shall see all these things, know that it is near, even at the doors.  Verily I say unto you, This generation shall not pass, till all these things be fulfilled.  Heaven and earth shall pass away, but my words shall not pass away.  But of that day and hour knoweth no man, no, not the angels of heaven, but my Father only.  (Matthew 24:33-36)

Here he speaks of &quot;these things&quot; and &quot;this generation&quot; in contradistinction to &quot;that day and hour&quot;.  He is saying I know this generation is going to see these things take place; but nobody knows about that time when the end of the age will be.
Matthew 24:36 has a parallel verse in Mark 13:32 which adds an extra interesting portion:-

But of that day and that hour knoweth no man, no, not the angels which are in heaven, neither the Son, but the Father.

The time of the end of the age, when our Lord returns, has not even been revealed to our Lord as he is a man.  Hence it is that he calls us to be always ready for his second coming for &quot;we do not the hour&quot;, Matthew 24:42-44.
So when he talks of &quot;this generation&quot; in Matthew 24:34 he is speaking of the time of the destruction of the Temple: the Temple was destroyed at the end of the Jewish Rebellion in 70 AD.
But he is not giving a time of when he shall return to judge the living and the dead because he does not know.  His human nature has not been given this information.
This interpretation can found in the Matthew Henry's Commentary from the early 18th century.