Colloquial translation of "preaching to the choir"? The phrase preaching to the choir is explained nicely in Wikitonary:

Verb
preach to the choir
(idiomatic) To speak as if to convince a person or group of something they already believe. quotations ▼
Usage notes
Often used to imply that a speaker is addressing the wrong audience or is deliberately addressing a compliant, non-challenging audience.

The first translation on YouDao translates it very literally:

给唱诗班传道

the second translation is completely wrong (你和唱诗班说吧) and the third is quite literal as well:

对唱诗班说教

While, seemingly, correct - the above translations could hardly express the nuances of addressing the wrong audience by trying to convince them of something they already believe in Chinese.
Any ideas for a good colloquial translation of &quot;preaching to the choir&quot;?

ed: 给和尚念经 -or- 念经给和尚听 are quite good alternatives!
I would say the Chinese 4 characters idom "班门弄斧" could be best for "preaching to the choir".

“班门弄斧" basically means "display one's slight skill before an expert." "班" here represents the best carpenter in China ancient history whose name is '鲁班', '弄斧' means display somebody's axe skill.

Another one comes into my mind  is '关公面前耍大刀', '关公' was a big hero in China ancient history who can do '大刀broadsorwd' very well, and if you show your sword skill before him, that's really not a right thing.