Luke 2:43

And fulfilling the days, as they returned, the boy Jesus stayed in Jerusalem. And Joseph and His mother did not know.

Exodus 12:15

You shall eat unleavened bread seven days; even the first day you shall put away leaven out of your houses. For whoever eats leavened bread from the first day until the seventh day, that soul shall be cut off from Israel.

2 Chronicles 25:17

And Amaziah king of Judah took advice, and sent to Jehoash the son of Jehoahaz the son of Jehu, king of Israel, saying, Come let us look one another in the face.

2 Chronicles 30:21-23

And the sons of Israel found at Jerusalem kept the Feast of Unleavened Bread seven days with great gladness. And the Levites and the priests praised Jehovah day by day with loud instruments to Jehovah.

Treasury of Scripture Knowledge

Summary

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.

Bible References

General references

2 Chronicles 30:21
And the sons of Israel found at Jerusalem kept the Feast of Unleavened Bread seven days with great gladness. And the Levites and the priests praised Jehovah day by day with loud instruments to Jehovah.
2 Chronicles 25:17
And Amaziah king of Judah took advice, and sent to Jehoash the son of Jehoahaz the son of Jehu, king of Israel, saying, Come let us look one another in the face.