He never visits without a reason — he must want something from me.
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history
From the Ming-dynasty story collection 警世通言 (Stories to Caution the World). 三宝 (sān bǎo) = the Three Jewels of Buddhism (Buddha 佛, Dharma 法, Sangha 僧); 三宝殿 = the main hall of a Buddhist temple. People only entered to make offerings or ask blessings.
usage
Often said wryly when an old contact reaches out unexpectedly — both as a tease ('OK, what do you need?') and as a sincere acknowledgement that the person wouldn't ask without reason.