Luke 2:43

And having completed the days, in their returning the child Jesus remained in Jerusalem; and Joseph and his mother knew not.

Exodus 12:15

Seven days ye shall eat unleavened; wholly in the first day shall ye turn away leaven in your houses; for all eating leavened and that soul was destroyed from Israel from the first day even to the seventh day.

2 Chronicles 25:17

And Amaziah king of Judah will take counsel, and will send to Joash son of Jehoahaz, son of Jehu, king of Israel, saying, Come, we will see faces.

2 Chronicles 30:21-23

And the sons of Israel, those found in Jerusalem, will do the festival of the unleavened seven days, in great gladness: and the priests and the Levites praising to Jehovah day by day with instruments of strength 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, those found in Jerusalem, will do the festival of the unleavened seven days, in great gladness: and the priests and the Levites praising to Jehovah day by day with instruments of strength to Jehovah.
2 Chronicles 25:17
And Amaziah king of Judah will take counsel, and will send to Joash son of Jehoahaz, son of Jehu, king of Israel, saying, Come, we will see faces.