Matthew 23:30

and your boast is, "'If we had lived in the time of our forefathers, we should not have been implicated with them in the murder of the Prophets.'

Matthew 21:35-36

but the vine-dressers seized the servants, and one they cruelly beat, one they killed, one they pelted with stones.

Matthew 23:34-35

"For this reason I am sending to you Prophets and wise men and Scribes. Some of them you will put to death--nay, crucify; some of them you will flog in your synagogues and chase from town to town;

Treasury of Scripture Knowledge

Summary

And say, If we had been in the days of our fathers, we would not have been partakers with them in the blood of the prophets.

Bible References

The blood

Matthew 23:34
"For this reason I am sending to you Prophets and wise men and Scribes. Some of them you will put to death--nay, crucify; some of them you will flog in your synagogues and chase from town to town;
Matthew 21:35
but the vine-dressers seized the servants, and one they cruelly beat, one they killed, one they pelted with stones.