expression, suru verb (precursor)
to harm oneself by trying to harm another; to cut off one's nose to spite one's face
Idiomatic expression with a literal image of looking up and spitting, only for the spit to fall back on oneself. Used to describe self-defeating revenge or spite.
See also: 天に唾する
彼を困らせようとして、結局天を仰ぎて唾すようなことになった。
Trying to cause him trouble ended up being like cutting off my nose to spite my face.
「天を仰ぎて唾す」とは、人に害を与えようとして自分に返ってくることのたとえだ。
'Ten o aogite tsubakisu' is a metaphor for when an attempt to harm someone else backfires on oneself.