Matthew 14:7 - Matthew Poole's English Annotations on the Holy Bible

Mark relates this more fully, but the sense is the same, Matthew 6:21-23, And when a convenient day was come, that Herod on his birthday made a supper to his lords, high captains, and chief estates of Galilee; and when the daughter of the said Herodias came in, and danced, and pleased Herod and them that sat with him, the king said unto the damsel, Ask of me whatsoever thou wilt, and I will give it thee. And he sware unto her, Whatsoever thou shalt ask of me, I will give it thee, unto the half of my kingdom. Those who have got over the point of lawfulness in an action, have nothing to consult but convenience: therefore saith Mark, when a convenient day was come, when probably Herod should be over merry with wine, or should be busy with his company, and not so much at leisure to consider what he did. It so happened that the daughter of this Herodias danced before Herod upon his birthday. The keeping of birthdays was usual amongst the eastern kings; Pharaoh kept his birthday, Genesis 40:20. Some by it understand the day of the prince's coronation, or entrance upon his government, which some think is meant in Hosea 7:5, by the day of our king, (when) the princes made him sick with bottles of wine. The Jews reckoned them both amongst the pagan festivals, but they had derived both this and many other usages from them. Dancing was much used amongst them at their festivals, It seemeth this daughter of Herodias pleased Herod more than ordinary; he sweareth that he would give her what she would ask, to the half of his kingdom. That phrase, by Esther 5:3, seemeth to have been ordinary with princes when they made liberal promises.