Sirach's passage is all about the good and proper end of our freedom 

"If you choose you can keep the commandments, they will save you;
if you trust in God, you too shall live;
he has set before you fire and water
to whichever you choose, stretch forth your hand..."

The Psalm offered to us by the Church is: " Blessed are they who follow the law of the Lord!"

St Paul speaking to the Corinthians reminds us of the virtue of Wisdom, a gift from the Holy Spirit, which helps our mind and soul be responsive to divine things, directing our mind to God. 

In St Matthew's Gospel, Jesus teaches us of the perennial personal value of the Old Testament, properly understood.  We apply the OT through the lens of Jesus, the perfection of the Law Himself.  He is the Word of God.