કાન સુણ્યું નવ માનીએ, નજરે ભાળ્યું સાચ;

kāna suṇyuṁ nava mānīē, najarē bhāḷyuṁ sāca;

Literally: Do not believe what is heard by the ear, what is seen with the eyes is true;
What it means: One should rely on direct observation rather than hearsay or rumors.

Also said as

ગુજરાતી કહેવતસંગ્રહ (Gujarati Kahevat Sangrah) (1923) · read from the scan by machine — the Gujarati itself is unchecked · English is machine-made and nobody has checked it yet

Heard it differently, or know we've got the sense wrong? Tell us — that is exactly the kind of correction this needs.