He was ungrateful when I helped him like this. What two-part allegorical saying or poem should be used instead?

Good intentions are not rewarded. Be kind and be a donkey's liver and lung

Falling flowers deliberately follow the running water, and the running water loves falling flowers mercilessly.

I turn my heart to the bright moon, which shines on the ditch.

Those who know me make me worry, and those who don't know me make me want.

Be kind and give advice. If you can't stop, don't bring disgrace to oneself.