Rosh Hashanah, according to ancient tradition, is the day that God sits in judgment over all of His creatures, determining who shall live and who shall die. Thus the liturgy comprises both praise for God’s might and splendor in His role as judge, and appeals to His mercy and compassion. Surveying a number of midrashic sources, Akiva Mattenson notes a tendency in rabbinic thought to equate God’s might with His mercy. One prooftext, for instance, is Numbers 14:17, in which Moses introduces a plea for forgiveness with the words “And now let the strength of my Lord grow great.” In the rabbinic view, Mattenson explains,
what constitutes divine strength, what makes God unique and incomparable, is a capacity for compassion. This compassion sits in an uncomfortable tension with the rage that sets God against the enemies of Israel and the stern judgment that calls for unmitigated punishment. Yet it is precisely this tension that marks divine compassion as a [form of] strength. For it is only in mightily subduing a predilection for unmitigated judgment that God’s compassion emerges victorious. This is the meaning of the striking phrase found in one midrash, “For you subdue [kovesh] with compassion your quality of judgment.” [The Hebrew verb here is generally used to denote literal conquest or subjugation.]
There is struggle and conquest involved in the victory of compassion over divine judgment. The phrase calls to mind a teaching found in Pirkei Avot 4:1: “Who is mighty? The one who subdues [kovesh] his impulse, as it is said, ‘One slow to anger is better than a mighty person and one who rules his spirit than the conqueror of a city’ (Proverbs 15:16).” Just as human might emerges in the difficult . . . conquest of our impulse toward wickedness, divine might emerges in the difficult . . . conquest of God’s impulse toward judgment and anger. . . .
This notion that God is locked in a fierce struggle with His own tendency toward [giving sin its proper punishment], and is striving mightily to act compassionately with His creatures, comes to the fore in a beautiful text from the talmudic tractate of Brakhot, [which states that God regularly recites the following prayer]: “May it be My will that My compassion subdue my anger, and My compassion prevail over My [other] qualities, and that I behave with My children with My quality of compassion, and that I don’t hold them strictly to the letter of the law.”
Critically, God’s will for compassion rather than anger or judgment is couched in the language of prayer. . . . God’s prayer for compassion signals the degree to which victory against judgment and anger is not a foregone conclusion and the prevailing of compassion is something that will require effort and struggle.
Read more on Lehrhaus: https://www.thelehrhaus.com/timely-thoughts/rosh-hashanah-and-gods-battle-for-compassion/