expression, na-adjective, noun which may take the genitive case particle 'no', noun
reap what you sow; suffer the consequences of one's own actions; get one's just deserts
A yojijukugo used when someone experiences negative results that are clearly their own fault. Often said with a tone of 'you brought this on yourself'.
彼が失敗したのは自業自得だ。
It's his own fault that he failed.
遅刻して叱られたのは自業自得だ。
Getting scolded for being late is just reaping what you sow.