Reference for Berakhot 46:18

לא קשיא הא דאזמניה הא דלא אזמניה דאמר רב חסדא האי סודרא דתפילין דאזמניה למיצר ביה תפילין צר ביה תפילין אסור למיצר ביה פשיטי אזמניה ולא צר ביה צר ביה ולא אזמניה שרי למיצר ביה זוזי

There is no contradiction. The latter refers to one who has assigned [a place in his underwear in which to deposit his Tefillin]; the other refers to a man who has not assigned such a place. For Rab Hisda said : In the cloth in which one assigns to tie up his Tefillin one must not tie up coins, if he has already placed the Tefillin therein. If he assigned to tie up his Tefillin in it but has not bound them therein, or if he has bound up his Tefillin in the cloth without such assignment, he may tie up money therein.

Jastrow