Showing Mercy and Receiving Mercy

˃ְל ןַתָנְו וֹפַּא ןוֹרֲחֵמ 'ה בוּשָׁי ןַעַמְל םֶרֵחַה ןִמ הָמוּאְמ ˃ְדָיְבּ קַבְּדִי אֹלְו ˃יֶתֹבֲאַל עַבְּשִׁנ רֶשֲׁאַכּ ˃ֶבְּרִהְו ˃ְמַחִרְו םיִמֲחַר: דברים פי"ג פי"ח

And nothing of that which was devoted to destruction shall remain in your hand; that the Lord may turn from the fierceness of his anger, and show you mercy, and have compassion upon you, and multiply you, as he has sworn to your fathers. {13:18}

Rebbi Gamliel the son of Rebbi says: “And He will show you mercy and be merciful towards you” - this teaches that anyone who shows mercy to others is shown mercy from Shomayim {Heaven}, and anyone who does not show mercy to others is not shown any mercy from Shomayim.”

Talmud Bavli, Shabbos 151: