Luke 2:41-43, 46-47

And his parents went every year to Jerusalem at the feast of the passover. And when he was twelve years old, they went up after the custom of the feast; and when they had fulfilled the days, as they were returning, the boy Jesus tarried behind in Jerusalem; and his parents knew it not

And it came to pass, after three days they found him in the temple, sitting in the midst of the teachers, both hearing them, and asking them questions: and all that heard him were amazed at his understanding and his answers.