Mark 6:23 (KJV)

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.

And she went forth, and said unto her mother, What shall I ask? And she said, The head of John the Baptist.

And she came in straightway with haste unto the king, and asked, saying, I will that thou give me by and by in a charger the head of John the Baptist.