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.
Luke 2:42-50 New International Version (NIV)
42 When he was twelve years old, they went up to the festival, according to the custom. 43 After the festival was over, while his parents were returning home, the boy Jesus stayed behind in Jerusalem, but they were unaware of it. 44 Thinking he was in their company, they traveled on for a day. Then they began looking for him among their relatives and friends. 45 When they did not find him, they went back to Jerusalem to look for him. 46 After three days they found him in the temple courts, sitting among the teachers, listening to them and asking them questions. 47 Everyone who heard him was amazed at his understanding and his answers. 48 When his parents saw him, they were astonished. His mother said to him, “Son, why have you treated us like this? Your father and I have been anxiously searching for you.”
49 “Why were you searching for me?” he asked. “Didn’t you know I had to be in my Father’s house?”[a] 50 But they did not understand what he was saying to them.