Comment on The Christian’s Death. Christian Hymn by David Law.
I created this site a while ago from an out of print out of copyright book from Project Gutenberg: http://www.gutenberg.org/files/20476/20476-8.txt
Hymns for Christian Devotion, by J.G. Adams and E.H. Chapin
Scroll to page 544. or search for “Behold the western evening light!” to find the particular text.
The book was published in 1853, but it’s the 22nd edition so presumably much older.
No idea about it’s origin.
Since you are interested in the last 4 lines (might not be unique to this text) you can use “speech marks” in Google to limit what you search for: Basically search for the line below in Google.
“Night falls, but soon the morning light”
It’s less than 200 results, maybe one of them has the origin.