Whereupon he promised with an oath
On account of her fine dancing, and being extremely pleased with it himself; and the more, that it gave such pleasure to the whole court: he first promised her,
to give her whatsoever she would ask;
and then repeating it, he confirmed it with an oath; adding, as Mark says, that he would give it her, even "to the half of his kingdom": a way of speaking used by princes, when they give full power to persons to ask what they will of them; and to express their great munificence and liberality; signifying, let it be ever so great, or cost what it will, though as much as half a kingdom comes to, it shall be granted; see ( Esther 5:3 Esther 5:6 ) . A very foolish promise, and a rash oath these, which were made upon such a consideration, as only a fine dance. If she, as Theophylact observes, had asked for his head, would he have given it her? And if he swore by his head, which was a common form of swearing with the Jews F21, she very appropriately, though unjustly, as Dr. Lightfoot observes, answers to him; as you have swore by your head, give me John Baptist's head.