הלכה על ברכות 28:31

Every Jewish man is obligated to make sure that there will be the Tefillin upon him during Kriyat Shema and Prayer (Amidah/Shemoneh Esreh). And anyone who says Kriyat Shema without Tefillin — it is as if he has testified falsely against himself, and as if he has sacrificed a sacrifice without the libations (Berachot 14b). That is to say: that the false testimony is that he says "And you shall bind them [the Tefillin] as a sign upon your arm..." — and he didn't bind them! And also the Kriyat Shema that he said only counts as half a Mitzvah, like one who sacrifices a sacrifice without the libations. And until when the Tefillin should be upon him will be explained at the end of this chapter, that they should be upon him until after "Aleinu", see there.