והיה לאות על ידכה ולטוטפת בין עיניך כי בחזק יד הוציאנו ה' ממצרים ... (יג-טז)
Chazal draw attention to the spelling of the word "ידכה" pointing out that it’s not only unique, but also different than its spelling in פסוק ט. They extrapolate from this the halacha that the tefillin must be worn on the weaker hand, the יד כהה. Perhaps, al pi drush, we can offer the following explanation: While enslaved and tortured, the Bnei Yisroel were on a spiritually low level at that juncture. They had stooped to the 49th level of impurity. Nevertheless, Hashem, in His infinite kindness and wisdom, took us out of the shibud of Mitzrayim. That is a sure sign that during future exiles, Hashem will again redeem us, even if and when we aren’t worthy. Thus, the tefillin shel yad, representing HKB”H’s outstretched arm, is a sign that even when we are weak - יד כהה - we can and will be redeemed.
The Gemara in Brachos (6a) tells us that Hashem too dons tefillin daily. Inside those Divine batim, the parshiyos speak of the tremendous love Hashem has for us. The tefillin shel rosh corresponds to the mind, the thought process and hashgacha. There are 4 compartments in the shel rosh, representing 4 different classes and levels of Yidden. Hashem’s “mind”, so to speak, His hashgacha, varies depending on the level of each Yid. The shel yad, however, contains just one compartment. This symbolizes that the shel yad, which is placed opposite the heart, can encompass all types of individuals, in all walks of life. Hashem’s heart, His love for each and every one of us, doesn’t discriminate. He loves us all equally and endlessly. Perhaps this is another pshat to explain that just as then - in Mitzrayim - He showed His love for us disregarding our lowly state of tumah, so too now, the shel yad will be that sign that even the יד כהה of Yidden - the weaker ones - are so beloved by Hashem.
Let us too be meshabeid our lev to Him showing our absolute love for Hashem, and to each and every Jew unconditionally! And in that zechus may we merit the geula shelaima b’karov mamash!