It is a necessity. Prayer arises out of the new life of Jesus Christ that God gives. God makes known to us our needs and our helplessness as His children. And we must arise and go to our Father. To neglect to pray is to neglect to breathe spiritually.
Prayer is the mark of a genuine faith and conversion.
The man who only days before was riding to Damascus on the devil's business, breathing out threats and slaughter to Christians, now has repented in dust and ashes. Yes, all of those things will also be the sure mark of God's work in the life of the apostle Paul. When we look a little more closely at this verse we see that it is given as the reason why Ananias should arise and go to Saul. Saul, when he was converted, was blinded. He came to Damascus and stayed in the house of Judas.