不怕不识货，就怕货比货
bù​pà​bù​shí​huò​jiù​pà​huò​bǐ​huò

the value of things is only clear by comparison

不怕不识货，就怕货比货 不怕不識貨，就怕貨比貨 bù​pà​bù​shí​huò​jiù​pà​huò​bǐ​huò
the value of things is only clear by comparison
Literally, do not fear not knowing the quality of goods, but only fear comparing them; it means that the true value of a person or object can only be determined through comparison with others.