When Jesus came near Jerusalem, He
wept over the city because the people
had rejected Him and He knew it meant
judgment for them. Read Luke 19:41-44

Later in Luke 21:32 that generation would
pass away when an enemy would come
against it and destroy them.

They had been persecuting the christians.

It happened as Jesus said it would 40
years later. Titus broke through the walls
and destroyed the city.