Then to those who call upon him for help he can impart the health-giving power of God's truth. He can talk of the works of healing wrought by Christ, and direct the minds of the sick to Him as the great Physician, who is light and life, as well as comfort and peace. He can tell them that they need not despair, that the Saviour loves them, and that if they surrender themselves to Him, they will have His love, His grace, His keeping power. Let him urge them to rest in God's promises, knowing that He who has given these promises is our best and truest Friend. As he endeavors to direct the mind heavenward, he will find that the thought of the tender sympathy of the One who knows just how to apply the healing balm, will give the sick a sense of rest and quietude. GW 214.2 The divine Healer is present in the sick-room; He hears every word of the prayers offered to Him in the simplicity of true faith. His disciples today are to pray for the sick, as verily as did the disciples of old. And the…
"And the prayer of faith shall save the sick, and the Lord shall raise him up; and if he have committed sins, they shall be forgiven him."
Ellen White directly references James 5:15 in this passage.
***** In the word of God we have instruction relative to special prayer for the recovery of the sick. But the offering of such prayer is a most solemn act, and should not be entered upon without careful consideration. In many cases of prayer for the healing of the sick, that which is called faith is nothing less than presumption. GW 215.2 Many persons bring disease upon themselves by their self-indulgence. They have not lived in accordance with natural law or the principles of strict purity. Others have disregarded the laws of health in their habits of eating and drinking, dressing or working. Often some form of vice is the cause of feebleness of mind or body. Should these persons gain the blessing of health, many of them would continue to pursue the same course of heedless transgression of God's natural and spiritual laws, reasoning that if God heals them in answer to prayer, they are at liberty to continue their unhealthful practices and to indulge perverted appetite without restrain…
"Is any sick among you? let him call for the elders of the church; and let them pray over him, anointing him with oil in the name of the Lord:"
Both passages discuss prayer for the sick. EGW expands on the conditions under which such prayer is effective, adding a layer of interpretation to the practice mentioned in James.
"And the prayer of faith shall save the sick, and the Lord shall raise him up; and if he have committed sins, they shall be forgiven him."
Both passages discuss prayer for the sick and the forgiveness of sins. EGW elaborates on the connection between sin, health, and the efficacy of prayer, building upon the concept introduced in James.
"It is labor lost to teach people to look to God as a healer of their infirmities, unless they are taught also to lay aside unhealthful practices. In order to receive His blessing in answer to prayer, they must cease to do evil and learn to do well. Their surroundings must be sanitary, their habits of life correct. They must live in harmony with the law of God, both natural and spiritual. GW 215.4"
"Wash you, make you clean; put away the evil of your doings from before mine eyes; cease to do evil;"
EGW directly quotes and applies the principle of ceasing to do evil from Isaiah 1:16 in the context of healing and receiving God's blessing.