по собственному

of one's own accord

→ по

phrase Rare #54,046

of one's own accord Usually used with a following noun, such as желанию (desire) or воле (will); the adjective changes form to match that noun.

RU: Он ушёл по собственному желанию.

EN: He left of his own accord.

Those who are willing to kill at will.

— Кролик Джоджо (2019)