ફેર ન વહી હે કપટસોં, જો કીજે વ્યાપાર;

phēra na vahī hē kapaṭasōṁ, jō kījē vyāpāra;

Also said as

ગુજરાતી કહેવતસંગ્રહ (Gujarati Kahevat Sangrah) (1923) · read from the scan by machine — the Gujarati itself is unchecked · awaiting its meaning

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