Placing our full trust in God, our full faith in God's work for salvation, has real life consequences, meaning, we put our lives in His Hand in love - and we seek out of love to do what is pleasing to Him.
Works aren't done in return for eternal life (a slaves wage) they are born out of love for our Father who so greatly loved us as to give us such a precious gift in His Son.
The Pharisees trusted in themselves, in their works, in their understanding of prophecy, in how other men saw them - what they failed to do was to trust in Him, in His works, in His actions, in His interpretation, in His Son... because they were focused on self, and trusting in their actions while failing to see their actions were futile in the face of a sovereign God and their acts of righteousness were as filthy rags to that which is Holy.
You can't say do works, without first showing what is love.