I Samuel 14:13-15

And Jonathan climbed up on his hands and knees with his armorbearer after him; and they fell before Jonathan. And as he came after him, his armorbearer killed them. That first slaughter which Jonathan and his armorbearer made was about twenty men within about half an acre of land. And there was trembling in the camp, in the field, and among all the people. The garrison and the raiders also trembled; and the earth quaked, so that it was a very great trembling.