There can be very unfortunate misunderstanding with regard to this question which has kept some evangelicals from ministering to the infirm as Jesus commanded his disciples.
When Jesus had called the Twelve together, he gave them power and authority to drive out all demons and to cure diseases, and he sent them out to proclaim the kingdom of God and to heal the sick. (Luke 9:1-2)
After this the Lord appointed seventy-two others and sent them two by two ahead of him to every town and place where he was about to go. …Heal the sick who are there and tell them, ‘The kingdom of God has come near to you.’ (Luke 10:1 & 9)
In these passages, Jesus gave authority and power over demons and diseases to the 12 disciples and then to the 72 disciples before sending them out to proclaim the kingdom of God to the lost. They were to use this authority over diseases by directly commanding the infirmity or the sick person to be healed in the name of Jesus Christ—just as Jesus did time and time again in the gospels. The miraculous healing would be the evidence that Jesus was in fact the promised Messiah.
They were by no means commanding God to heal. Rather they were issuing commands to demons and diseases—over which the Lord had given them authority.
In Acts the disciples continued to use this authority and power to heal the sick and cast out demons.
In Lystra there sat a man who was lame. He had been that way from birth and had never walked. He listened to Paul as he was speaking. Paul looked directly at him, saw that he had faith to be healed and called out, “Stand up on your feet!” At that, the man jumped up and began to walk. (Acts 14:8-10)
Once when we were going to the place of prayer, we were met by a female slave who had a spirit by which she predicted the future. She earned a great deal of money for her owners by fortune-telling. She followed Paul and the rest of us, shouting, “These men are servants of the Most High God, who are telling you the way to be saved.” She kept this up for many days. Finally Paul became so annoyed that he turned around and said to the spirit, “In the name of Jesus Christ I command you to come out of her!” At that moment the spirit left her. (Acts 16:16-18)
It is clear that when Paul exercised authority over the infirmity in Acts 14 and then the spirit in Acts 16, he was NOT speaking to God commanding Him to heal or to drive out the demon, but rather issuing commands directly to the lame man and then to the spirit.
A simple illustration
Let’s say you have a pet dog in your home. God has clearly given you authority over your dog. When you want your dog to sit, you issue a command to him to “sit.” When you do this you are of course not commanding God. Rather you are simply exercising the authority God has given you over your pet.
In the same way, Jesus has given his disciples authority over diseases for the sake of proclaiming the kingdom of God to the unbelieving lost. Therefore today when we exercise authority and power over infirmities in the name of Jesus Christ to minister healing to the sick, we are NOT commanding God. Rather we are simply exercising authority over the infirmity which God has placed under our authority for the sake of confirming the truth of the gospel to the lost. We speak directly to the infirmity or the sick person with authority. Once again, the purpose of the miraculous healing is to provide evidence to the lost that Jesus is the Son of God and the only way to the Father.
According to Scripture, the early disciples were not familiar with “healing prayer” as is done today