天てんに唾つばする

expression, suru verb (special)

harm oneself by trying to harm others; cut off one's nose to spite one's face

Idiomatic expression; literally 'to spit at the sky', meaning that an attempt to harm someone else backfires and hurts oneself instead.

• 彼かれを陥おとしいれようとしたが、天てんに唾つばする結けっ果かになった。

  He tried to bring him down, but it ended up being a case of cutting off his nose to spite his face.

• そんなことをすれば天てんに唾つばするようなものだ。

  Doing that would be like spitting at the sky.