1 Samuel 31:5

And when his armourbearer saw that Saul was dead
By his own hands, and not by the hands of the Amalekite, which the armour bearer would scarcely have suffered:

he fell likewise upon his sword, and died with him;
some think that Saul, and his armourbearer, died by the same sword, which was the armourbearer's; and if he was Doeg, they fell probably by the same sword with which the priests of the Lord were murdered at Nob, ( 1 Samuel 22:18 ) ; and it is observed by an historian ^F4, that the murderers of Julius Caesar slew themselves with the same dagger they destroyed him.