Luke 2:43-47 New English Translation (NET)

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,

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.

45. When they did not find him, they returned 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. And all who heard Jesus were astonished at his understanding and his answers.

Luke 2