This hymn text is rooted in the early Christian church, all the way back to the Greek-language Didache (the Teaching of the Twelve Apostles), a Christian manual from the Church of Antioch, Syria, which some scholars date as early as A.D. 110. To produce this hymn text, F. Bland Tucker translated selected prayers from chapters 9 and 10 of the Didache.
Stanzas 1 and 2a are from a post-communion prayer, and stanza 2b is from a prayer intended during distribution of the bread. The whole is essentially a hymn of thanksgiving and praise (st. 1) concluded with a petition for the unity of the church (st. 2), which reminds us of Christ's prayer that all believers "may be one" (John 17:21). That unity should be obvious when Christians gather around the Lord's table, but it should also extend within and between Christian denominations.
Bert Polman, Psalter Hymnal Handbook