וּכְתַבְתָּ֛ם עַל־מְזוּזֹ֥ת בֵּיתֶ֖ךָ וּבִשְׁעָרֶֽיךָ׃ (ס)
И напиши их на дверных столбах дома твоего и на воротах твоих.
Shenei Luchot HaBerit
Although the phylacteries are placed on the left arm, this does not denigrate the right arm; it is required in order that the phylacteries may be placed on the left arm. The right hand is the hand with which both the writing of the portions of Torah within the phylacteries and the tying of the knots is performed. The right hand thus has in no way been denigrated when it comes to the performance of the מצוה of תפילין.