וְשָׁמַרְתָּ֛ אֶת־הַחֻקָּ֥ה הַזֹּ֖את לְמוֹעֲדָ֑הּ מִיָּמִ֖ים יָמִֽימָה׃ (ס)
Thou shalt therefore keep this ordinance in its season from year to year.
Targum Jonathan on Exodus
Thou shalt therefore keep this statute of the Tephillin in the season to which it belongs, on work days, not on sabbaths or solemnities; and by day, not by night.