He is talking about the works of the old mosaic law not Christian fruits( works) new testament works. You will know them by there fruits.
You insert (works) because why? Are you trying to inject a meaning?
“Then said they unto him, What shall we do, that we might work the works of God? Jesus answered and said unto them, This is the work of God, that ye believe on him whom he hath sent.” John 6:28-29