Hail, happy day! the [thou] day of holy rest. S. Browne. [Sunday.] First published in his Hymns & Spiritual Songs, &c, 1720, Bk. iii. No. 1, in 9 stanzas of 4 line, and headed, "For the Lord's Day," It is in several modern American collections, altered and abbreviated, as in the Songs for the Sanctuary, 1865, No. 71, where it reads, "Happy day! thou day of holy rest." The stanzas chosen are i., ii. and iv.
--John Julian, Dictionary of Hymnology (1907)