PRESSLY is one of the many (now often forgotten) hymn tunes and gospel songs composed by Charles H. Gabriel (PHH 24). With a copyright date of l901, the tune first appeared with this text in the 1912 Psalter.
Sing in harmony as a testimony of our harmonious love! Well-trained choirs should lead the congregation in singing this hymn in two long lines rather than six short phrases.
--Psalter Hymnal Handbook