You hear it occasionally. Somebody explaining that, since we live under the New Testament covenant, the only purpose the Old Testament serves is to help us understand history and to supply us with stories of faith. They point out that we no longer serve under the rules of the Law, so none of that is necessary for the Church to know.
That wasn’t the opinion of the first church leaders.
The Old Testament was the only Bible they had. Using the Old Testament book of Isaiah, Philip taught a government official about Jesus, and convinced him to be baptized. Paul used the book of Deuteronomy to prove that churches should pay the preachers that serve them (I Corinthians 9:9-10). He also told Timothy that those Old Testament scriptures would lead us to salvation through faith in Christ Jesus, and that they would make a man of God perfect, giving him all the tools he needed to fulfill his calling (II Timothy 3:15-17).
Jesus admonished men to search those Old Testament scriptures, saying that they testify of Him.