In Masechet Menachot, there is a very rich section that deals with the laws of tefillin and mezuzah.   A particular theme of interest, especially in the context of the korban Pesach, is that of the mezuzah as an object that protects the house.   This idea is never stated in the Torah.  To the contrary, the Torah juxtaposes the mitzvah of mezuzah with that of tefillin and of constant Torah study.  The message is clear – have reminders of God all around you,  think of God and God’s mitzvot, and learn Torah at all times – when you