断る
ことわる · kotowaru · JLPT N3 · verb-godan
to refuse
✋ 断 = cut off; kotowaru comes from koto + waru, to split up the matter
The kanji 断 means to cut or sever, as in 断絶 (severance). Kotowaru is thought to come from 事割る, to divide up a matter and give your reasons. Refusing someone means explaining yourself and then cutting the request off.
断 — thread 㡭 (silk bundle) + axe 斤
Originally written with 㡭 (entangled silk threads) on the left and 斤 (axe) on the right, depicting an axe cutting through bundled threads. From this concrete image of severing came the meanings 'to cut off,' 'to break,' and by extension 'to decide' or 'judge'—as in resolving a matter decisively.