And when He was twelve years old, they went up to Jerusalem according to the custom of the feast. When they had finished the days, as they returned, the Boy Jesus lingered behind in Jerusalem. And Joseph and His mother did not know it; but supposing Him to have been in the company, they went a day’s journey, and sought Him among their relatives and acquaintances. So when they did not find Him, they returned to Jerusalem, seeking Him. Now so it was that after three days they found Him in the temple, sitting in the midst of the teachers, both listening to them and asking them questions. And all who heard Him were astonished at His understanding and answers.
So when they saw Him, they were amazed; and His mother said to Him, "Son, why have You done this to us? Look, Your father and I have sought You anxiously."
And He said to them, "Why did you seek Me? Did you not know that I must be about My Father's business?"
But they did not understand the statement which He spoke to them.
Luke 2:42-50 (NKJV)