The question is, when did he grant such authority to anyone BUT his apostles? How can you grant one person the authority to make free, and another person the same authority to bind? That’s nonsensical. Jesus gave this authority to Peter, and collectively, to his apostles. They, then, delegated this authority to their successors, and appointed episcopi. With a hierarchy, each episcopus (bishop) has authority within a certain see (jurisdiction); Without a hierarchy, there is no defined jurisdiction. Without a defined jurisdiction, you can have no authority.
The simple answer is when Jesus was asked to teach us to pray in Matthew 6:8-14.
8 Therefore do not be like them. For your Father knows the things you have need of before you ask Him. 9 In this manner, therefore, pray:
Our Father in heaven,
Hallowed be Your name.
10 Your kingdom come.
Your will be done
On earth as it is in heaven.
11 Give us this day our daily bread.
12 And forgive us our debts,
As we forgive our debtors.
13 And do not lead us into temptation,
But deliver us from the evil one.
For Yours is the kingdom and the power and the glory forever. Amen.
14 For if you forgive men their trespasses, your heavenly Father will also forgive you. 15 But if you do not forgive men their trespasses, neither will your Father forgive your trespasses.
Binding and loosing is not a power or authority one possesses. It is the result of our actions.
We loose our sins against our Heavenly Father by forgiving the sins of a brother against us. We keep them bound when we don't forgive.
If I ask you to forgive a sin I have committed against you, and you comply, we are both loosed of that sin. Jesus explains in Matthew 18
Notice Jesus ends with binding and loosing in context. You have to forgive to be forgiven.
Only the brother who is sinned against has the ability to forgive the sin. He is the only one whose sins against God are bound as a consequence of his non forgiveness. Nowhere does Jesus give any authority to the church.
Let's look at what Jesus told Peter about forgiving sins.
I may have missed it but this looks to me like Jesus told Peter he had to forgive a brother who sinned against him, Peter. Not a special gift but a command.
I am still waiting for someone to show me where Jesus specifically gave a man the ability to forgive another man's sin against God for God. Maybe you would be so kind.
May God the Father lead us to His truth, BVB