Luke 2:45

And when they had fulfilled the days, as they returned, the child Jesus tarried behind in Jerusalem; and Joseph and his mother knew not [of it].

But they, supposing him to have been in the company, went a day's journey; and they sought him among [their] kinsfolk and acquaintance.

And it came to pass, that after three days they found him in the temple, sitting in the midst of the doctors, both hearing them, and asking them questions.

And all that heard him were astonished at his understanding and answers.