11:22 If a Jew moves out of a house and is aware that another Jew is moving in, he should not take the mezuzos with him. The mezuzos should be left for the new tenant, who is expected to pay for them. 11:23 One must be very careful with the mitzvah of mezuzah since it is a constant, ongoing obligation for everyone. By performing the mitzvah of mezuzah, one will encounter a reminder of God’s unity and His love for us whenever he enters or leaves his house. This is meant to arouse us from our complacency and to turn us in the proper direction. The Talmud in Menachos (43b) says that whoever has tefillin on his body, tzitzits on his clothes and a mezuzah on his door will not sin because he has constant reminders.