Tefillin1 are boxes containing Torah verses, worn by Jews on the head and the upper arm, in accordance with instructions in Exodus 13:9, 13:16, and Deuteronomy 6:8, 11:18. There is a great deal of commentary in the Talmud and elsewhere about exactly how this should be done.
Jesus says that the Pharisees were ostentatious in their wearing of tefillin - Matthew 23:5 (NIV) reads:
Everything they do is done for people to see: they make their phylacteries1 wide and the tassels on their garments long.
It seems from Mt 9:20, 14:36, Mk 6:56 that Jesus may have worn the same kind of fringes or tassels (tzitziyot), similarly commanded in the Law, albeit presumably his were not as long as those of the Pharisees.
Would Jesus also have worn tefillin, and why/why not? If he did (and his disciples too?) then when did Christians stop? If he didn't, then was this unusual or scandalous?
1 Tefillin (תפילין), or totafot (טוטפת), or phylacteries (φυλακτήρια)