Reference for II Kings 6:31

וַיֹּ֕אמֶר כֹּֽה־יַעֲשֶׂה־לִּ֥י אֱלֹהִ֖ים וְכֹ֣ה יוֹסִ֑ף אִֽם־יַעֲמֹ֞ד רֹ֣אשׁ אֱלִישָׁ֧ע בֶּן־שָׁפָ֛ט עָלָ֖יו הַיּֽוֹם׃

Then he said: ‘God do so to me, and more also, if the head of Elisha the son of Shaphat shall stand on him this day.’