It was a common saying among the old Puritans, Brown bread and the gospel are good fare.
The Worthy Sayings of Old Mr. [John] Dod, p. 32:
Brown bread with the Gospel is good fare.
Old Mr. Dod's Sayings, p. 16:
Though we have things below, very rare / Yet brown bread with the Gospel is good fare.
Robert Leighton, Exposition of the Lord's Prayer, in Works, Vol. 4, p. 91:
Though he hath no more of the world but daily bread, and of the coarsest sort, he hath a continual feast within, as he that said, Brown bread and the gospel is good fare.
John Spencer, Things New and Old, Vol. 1, p. 20:
Brown bread and the Gospel (said Mr. [Richard] Greenham), is good cheer; and indeed, brown bread, and the blessing of God, is a rich banquet.