Luke 2:41-45

41And his parents went yearly to Jerusalem at the feast of the passover.

42And when he was twelve years old, and they went up [to Jerusalem] according to the custom of the feast

43and had completed the days, as they returned, the boy Jesus remained behind in Jerusalem, and his parents knew not [of it];

44but, supposing him to be in the company that journeyed together, they went a day's journey, and sought him among their relations and acquaintances:

45and not having found him they returned to Jerusalem seeking him.