不遗余力 (不遺餘力) bù yí yú lì

bù yí yú lì set phrase to spare no pains or effort / to do one's utmost
Domain: Idiom 成语
Notes: (CC-CEDICT '不遺餘力'; CCI '不遗余力', p. 122-123; Guoyu '不遺餘力')