Chazal
Chazalמְלַמֵּד שֶׁשְּׁפִיכוּת דָּמִים הוּא אֶחָד מִן הַדְּבָרִים שֶׁנִּפְרָעִין מִן הָאָדָם בָּעוֹלָם הַזֶּה וְהַקֶּרֶן קַיֶּמֶת לָעוֹלָם הַבָּא, דִּכְתִיב וַיֹּאמֶר קַיִן גָּדוֹל עֲוֺנִי מִנְּשֹׂא.
This teaches that bloodshed is one of the things for which a person is punished in this world while the principal remains for the world to come, as it is written “And Kayin said, My iniquity is too great to bear.”