R. Yonah: Here it is put next to "do not say 'I will pay evil'" (22). Hashem despises one who has a large and small stone [weights]. If someone stole from you, do not lose your honesty in order to be paid from him. Do not have a large stone to buy from him, and a small stone to sell to him. Or, to sell to your friend with the big stone ¹ , and to your hater and the one who did evil to you with the smaller, for Hashem detests fraud and theft. Chazal said, do not enter your colleague's property to take what is yours without permission ² . Perhaps you will appear like a thief to him! Rather, blunt his teeth and say 'I am taking what is mine!' (Bava Kama 27b)

Malbim: If someone sold to you with a fake weight via different stones, and you want to sell to him with a fraudulent scale, know that different stones are To'avas Hashem, and also payment via a fraudulent scale is not good. Hashem warned against these in every case - "Even va'Aven Eifah v'Eifah To'avas Hashem Gam Sheneihem" (10)!