Words by John H. Sammis, 1887 Music by Daniel B. Towner
Interestingly, the concept for this hymn was provided by the Daniel Towner, composer of the music, as he relates it in the 1906 book, The Story of the Gospel Hymns by Ira D. Sankey.
Mr. [Dwight L.] Moody was conducting a series of meetings in Brockton, Massachusetts [presumably in 1886] and I had the pleasure of singing for him there. One night a young man rose in a testimony meeting and said, "I am not quite sure--but I am going to trust, and I am going to obey." I just jotted that sentence down, and sent it with the little story to the Rev. John H. Sammis, a Presbyterian minister. He wrote the hymn, and the tune was born.