Doing Good to the Wicked Is Doing Evil/ doing a fafour to someone bad is doing wrong
Helping a wicked person is as if you had done harm to yourself.
("The creatures say: 'If you did good to the wicked, you did evil; do not do good to the wicked, and evil will not come upon you'" — Vayikra Rabbah (Vilna), Acharei Mot, parasha 22)
Translation
Expression (Hebrew)
טוֹב לְרַע עָשִׂיתָ -רַע עָשִׂיתָ
Definition (Hebrew)
עֶזְרָה וְסִיּוּעַ לְאָדָם רַע כָּמוֹהָ כְּאִילּוּ עָשִׂיתָ רַע בְּעַצְמְךָ.
("הוּא דִּבְרָיְתָא אִמְרִי טָב לְבִישׁ עָבַדְתְּ בִּישֹׁא עָבַדְתְּ, טָב לְבִישׁ לָא תַּעֲבִיד וּבְיֵשׁ לָא מָטִי לָךְ"- וַיִּקְרָא רַבָּה (וִילְנָא) פָּרָשַׁת אַחֲרֵי מוֹת פָּרָשָׁה כב)