"Some plead their poor health—they would love to do if they had strength. Such have so long shut themselves up to themselves, and thought so much of their own poor feelings, and talked so much of their sufferings, trials, and afflictions, that it is their present truth. They can think of no one but self, however much others may be in need of sympathy and assistance. You who are suffering with poor health, there is a remedy for you. If thou clothe the naked, and bring the poor that are cast out to thy house, and deal thy bread to the hungry, “then shall thy light break forth as the morning, and thine health shall spring forth speedily.” Doing good is an excellent remedy for disease. Those who engage in the work are invited to call upon God, and He has pledged Himself to answer them. Their soul shall be satisfied in drought, and they shall be like a watered garden, whose waters fail not. 2T 29.1"
"Is it not to deal thy bread to the hungry, and that thou bring the poor that are cast out to thy house? when thou seest the naked, that thou cover him; and that thou hide not thyself from thine own flesh? Then shall thy light break forth as the morning, and thine health shall spring forth speedily: and thy righteousness shall go before thee; the glory of the Lord shall be thy rereward."
The EGW passage directly quotes Isaiah 58:7-8 and connects the act of helping the needy with improved health, explicitly referencing the biblical text.