King James Version
And when they had fulfilled the days, as they returned, the child Jesus tarried behind in Jerusalem; and Joseph and his mother knew not of it.English Standard Version
And when the feast was ended, as they were returning, the boy Jesus stayed behind in Jerusalem. His parents did not know it,New International Version
After the Feast was over, while his parents were returning home, the boy Jesus stayed behind in Jerusalem, but they were unaware of it.