Note: This is a double parsha (Matos-Masei), but it’s about Masei.
“And the congregation will save the killer from the redeemer, and they shall return him to the city of refuge where he will sit until the death of the Kohen Gadol who was anointed with the holy oil.” — Bamidbar 35:25
A “shogeg killer” is a person who unintentionally killed someone else. If this happens, the shogeg killer must flee to a city of exile.
The Mishneh says that because shogeg killers can only return home when the Kohen Gadol died, the Kohen Gadol’s mother must bring the shogeg food and clothes. Since she acted kindly toward them, she gave them a sense of gratitude so they wouldn’t pray for her son to die.
This Gemara doesn’t make much sense. The Kohen Gadol is one of the greatest men of his generation and a tzaddik. But the shogeg killer is seen as a person who must be exiled and cannot stay with the nation. The question is: Apparently if the shogeg killer prayed, his prayers might be accepted and then the Kohen Gadol would die. Why? The K”G is innocent, and the shogeg is only praying for his death so he can be free. Why should it be accepted?
Hashem created two systems of judgment: Din, strict justice, and rachamim, mercy. Rachamim takes in to account many factors, whereas din is very strict and is like cause and effect. Sometimes when Hashem judges, there is more rachamim, and sometimes, more din. Our prayers can change the balance and give more rachamim.
A great as the K”G may be, if he were judged only with din, even he wouldn’t survive.
When the shogeg killer davens, he is asking Hashem to have mercy on him and let him go home, and the only way that can happen is if the K”G dies. The prayers of the shogeg killer change what kind of judgment Hashem uses. Therefore, the K”G will deserve to die. So that’s why the Kohen Gadol’s mother should do everything she could to stop the shogeg from davening. She knew the power of tefillah.
This shows us the power of tefillah: We often think, “What difference does my tefillah make?” The answer is that it makes a huge difference. Maybe not for what you are asking for, but on the system of judgment applied to you under the circumstances. We daven to Hashem to change the system and use mercy, and not strict justice.