Xǔ rén yī wù, qiānjīn bù yí.

許人一物, 千斤不移。

Lit [Once] something is promised, a thousand catties [should] not move [it back].

Fig Once something is promised, it should never be taken back.

Note [Rhyme; note: literally, one jīn or “catty” is equal to one-half kilogram, but qiānjīn is figuratively taken to mean “a ton, a great weight”; note also the chengyu: yīnuò-qiānjīn, “a solemn promise”; see also hǎi yuè shàng kě qīng above and yī yǔ wéizhòng below.]

Topics chengyu PROMISES qiānjīn (wt.) rhyme yīnuò-qiānjīn