Tefillin by Day, Not on Shabbat Which Is Already a Sign

"And you shall keep this ordinance in its season, from days to days" (Exodus 13:10). "Days" and not nights; "from days" and not all days, excluding Sabbaths and festivals; these are the words of Rabbi Yose the Galilean. Rabbi Akiva says: this ordinance is stated only with regard to the Passover offering alone. Rabbi Akiva says: one might think a person should lay tefillin on the Sabbath and festivals; therefore Scripture teaches, "And it shall be for a sign" (Exodus 13:9), [tefillin is] for those who need a sign; this excludes Sabbaths and festivals, which are themselves a sign. Rabbi Elazar said: whoever lays tefillin after sunset transgresses a positive commandment. And Rabbi Yochanan said: he transgresses a negative commandment. All agree with what Rabbi [Avin said in the name of Rabbi Ilai], who said: wherever it says "take heed," "lest," or "do not," it is nothing but a negative commandment. And here they differ in this: one master holds that "take heed" in a negative context is a negative, while "take heed" in a positive context is a positive; and the other master holds that "take heed" in a positive context is also a negative. And Rabbi Elazar said: if it is to guard them, it is permitted. "And you shall keep the ordinance" [is fulfilled] when they recite a blessing after removing their tefillin, to keep His ordinances.