Deuteronomy 6:20
"And when thy son asketh thee in time to come, saying, What mean the testimonies, and the statutes, and the judgments, which the LORD our God hath commanded you?"
Cross References (ranked by relevance)
Exodus 13:14
And it shall be when thy son asketh thee in time to come, saying, What is this? that thou shalt say unto him, By strength of hand the LORD brought us out from Egypt, from the house of bondage:
Exodus 12:26
And it shall come to pass, when your children shall say unto you, What mean ye by this service?
Deuteronomy 6:7
And thou shalt teach them diligently unto thy children, and shalt talk of them when thou sittest in thine house, and when thou walkest by the way, and when thou liest down, and when thou risest up.