立军令状

Traditional (Taiwan): 立軍令狀

lìjūnlìngzhuàng ㄌㄧˋ ㄐㄩㄣ ㄌㄧㄥˋ ㄓㄨㄤˋ

    • to pledge solemnly to complete a task or accept the consequences

Character by character

Saying俗语俗語

Idiom惯用语 · Widely known

Literally
sign a military order pledge
Meaning
To make a solemn promise, often in writing, that you will complete a task or accept the consequences. Often used of taking on a tough assignment.

Sources