Luke 2:42-44
2:42 When he was twelve years old, they went up according to custom.
2:43 But when the feast was over, as they were returning home, the boy Jesus stayed behind in Jerusalem. His parents did not know it,
2:44 but (because they assumed that he was in their group of travelers) they went a day’s journey. Then they began to look for him among their relatives and acquaintances.