Charles Ellicott Commentary Judges 9:24

"that the violence done to the threescore and ten sons of Jerubbaal might come, and that their blood might be laid upon Abimelech their brother, who slew them, and upon the men of Shechem, who strengthened his hands to slay his brethren." — Judges 9:24 (ASV)

That the cruelty ... might come ... upon Abimelech. — Scripture is always most emphatic in the recognition of the Divine Nemesis upon wickedness, especially upon bloodshed.

Their blood be laid upon Abimelech. — Compare 1 Kings 2:5, Matthew 23:35, and the cry of the Jews in Matthew 27:25.