English: The hand tefillin is written on one hide, as it is said “it shall be for you a sign on your hand” — just as it is one sign outside, so one sign inside.
On the daf / in context: See the cited source for the full section.
Type of Learning
Derash on the verse.
What Is Learned
Hand tefillin contain the four passages in a single compartment on one piece of parchment.