(13:10) "from day to day": What is the intent of this? From "and it shall be to you as a sign," I would think that the nights, too, are included. And this would follow, viz.: Since mezuzah is a positive commandment and tefillin are a positive commandment, then just as we have learned that just as mezuzah obtains both in the daytime and at night; so tefillin, it is, therefore written "from day to day" — it obtains in the daytime and not at night.