The "sanctus" section of this tune appears to be an arrangement and abridgement of SANCTUS, #342 in Hastings' Manhattan Collection (1845), a scan of which can be seen here: https://archive.org/details/manhatt00hast/page/342/mode/2up. Several early instances of this tune credit the source of the sanctus as "Manhattan Coll."
- Garrett Herndon, from comment made by "A." on https://hymnstudiesblog.wordpress.com/2008/10/10/quoton-zion039s-glorious-summitquot/ dated April 8, 2022