His hymn "From Greenland's Icy Mountains" inspired missionaries to take the gospel to faraway places. This hymn represented what Reginald believed was God calling him to serve as a missionary in India.
In 1822 at age forty, Reginald was appointed to oversee the Church of England's ministries in India. While in the village of Trinchinopoly in 1826, he preached to a large crowd in the hot sun. Afterward he plunged into a pool of cool water, where he suffered a stroke and drowned.
His widow later discovered his fifty-seven hymns in a trunk, and she had them published. Among these hymns was Holy, Holy, Holy, Lord God Almighty based on Revelation 4:8-11, And they do not rest day or night, saying: "Holy, holy, holy, Lord God Almighty, Who was and is and is to come!"