Where does “صحیح” come from?

صحیح (Classical Persian) comes from Arabic صَحِيح — true; right, correct; genuine; sound, healthy.

Ancestry of “صحیح”, step by step

Step	Language	Word	Meaning
1	Arabic	صَحِيح	true; right, correct; genuine; sound, healthy

صحیح — Etymology, Origin & Word History | Etymology Explorer