Luke 2:42-50 King James Version (KJV)
42 And when he was twelve years old, they went up to Jerusalem after the custom of the feast.
43 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.
44 But they, supposing him to have been in the company, went a day's journey; and they sought him among their kinsfolk and acquaintance.
45 And when they found him not, they turned back again to Jerusalem, seeking him.
46 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.
47 And all that heard him were astonished at his understanding and answers.
48 And when they saw him, they were amazed: and his mother said unto him, Son, why hast thou thus dealt with us? behold, thy father and I have sought thee sorrowing.
49 And he said unto them, How is it that ye sought me? wist ye not that I must be about my Father's business?
50 And they understood not the saying which he spake unto them.