Midrash su Esodo 13:16

And it shall be for a sign upon thy hand (Exod. 13:16). Upon thy hand refers to the biceps. Between thine eyes refers to the top of the forehead. Where is that located? The school of R. Yannai said: It is the place on the child’s head where the child’s brain is seen to pulsate. The four passages included in the phylacteries are mentioned in Scripture. They are: Sanctify unto me (Exod. 13:2), And it shall be when the Lord shall bring thee (ibid. 13:11), Hear, O Israel (Deut. 6:4), And it shall come to pass, if ye shall hearken (ibid. 11:13). It is forbidden to have sexual relations in a home containing tefillin or a scroll of the Torah until they are put away in their container.²³Berakhot 25b. Rava said: When a cloak is over a chest, it is like a receptacle in a receptacle.