וַיֹּ֖אמֶר מֶ֣ה עָשִׂ֑יתָ ק֚וֹל דְּמֵ֣י אָחִ֔יךָ צֹעֲקִ֥ים אֵלַ֖י מִן־הָֽאֲדָמָֽה׃
And He said: ‘What hast thou done? the voice of thy brother’s blood crieth unto Me from the ground.
Read kabbalistic (mystical) interpretation of Genesis 4:10: and classical mystical sources.