Luke 2:43-45
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.
2:45 When they did not find him, they returned to Jerusalem to look for him.