Biblical authority to pray to other than God through Jesus. Two things you don't understand.
1. The Church does not need a Biblical authority to do anything. She already has all the authority anyone can want form Jesus directly: "whatsoever thou shalt bind upon earth, it shall be bound also in heaven: and whatsoever thou shalt loose upon earth, it shall be loosed also in heaven".
2. Prayer to saints is a prayer to God through Jesus.
It is not complicated.
A prayer asking a dead saint for intercession is a prayer to a saint and not to God through Jesus.
Paul warned his churches about those who would alter the Gospels. In the post you're responding to, Jesus said it clearly, without ambiguity and left no doubt about the procedure. Paul refused to let even someone fall at his feet.
Pray to God through the Christ and leave the saints alone.
This kind of alteration, expansion and misinterpretation of doctrine by man is precisely why Jesus criticized the Pharisees and scribes.
