A.T. Robertson Commentary Matthew 15:6

"he shall not honor his father. And ye have made void the word of God because of your tradition." — Matthew 15:6 (ASV)

Ye have made void the word of God (εκυρωσατε τον λογον του θεου). It was a stinging indictment that laid bare the hollow pretence of their quibbles about handwashing. Κυρος means force or authority, ακυρος is without authority, null and void. It is a late verb, ακυροω but in the LXX, Galatians 3:17; and in the papyri Adjective, verb, and substantive occur in legal phraseology like cancelling a will, etc. The moral force of God's law is annulled by their hairsplitting technicalities and immoral conduct.