הושיעה לו ימינו וזרוע קדשו – Hoshiah lo yemino u’zeroa kodsho. His own right hand and His holy arm have helped Him.
Ibn Yachya explains that, during yetzias Mitzrayim, the Egyptian exodus, Hashem used only “one hand” to effect the Jews’ freedom. This is underscored in Shiras ha’yam, Yemincha Hashem needari ba’koach; Yemincha Hashem tiraatz oyaiv, “Your right hand, Hashem, is glorious in power. Your right hand, Hashem, shatters the enemy” (Shemos 15:6). La’asid lavo, in the future, Hashem will redeem us with “both hands.” The Malbim explains that zeroa and yad have various connections. Zeroa is the upper arm which manipulates the forearm and hand. Indeed, the source of the hand’s strength is the upper arm. When alluding to Hashem's actions on behalf of Klal Yisrael, the Torah uses the “hand” and the “upper arm” as similes. When we merit and are worthy of Hashem's salvation, we are described as the upper arm, which gives strength to the hand – Hashem. Thus, Hashem’s actions on our behalf draw their strength from our merit. When we are not deserving, when our merits are lacking, Hashem's actions are called zeroa, because it derives its strength from Hashem's Divine mercy. In the future redemption, Hashem's salvation will emanate both from zeroa and yad, since all the power will emerge from Hashem's mercy – regardless of our merits.
