This piece is often attributed to Michael Praetorius, but I think it's in error. He wrote a round called "Jubilate Deo", and published it in Musarum Sionarum, but that is a different, more complicated piece.
I don't know where or when this one comes from, but it's pretty, and easy, and to my ear a plausible style for about 1600, whenever it was written. If you can enlighten me, please do!
It seems to appear sometimes with the last phrase - Alleluia - going up in the middle (giving a total range of an octave and a third) and sometimes going down in the middle (giving a total range of an octave and a sixth). We sing the former version, as it's easier to fit comfortably into everyone's ranges.
These are in A (start on A, three sharps, range is A to C). All are midi files.
These play the piece first in "unison" (only one voice) then twice through as a round. The first voice to enter is slightly louder than the others.
- Jubilate Deo, one line, in C (pdf)
We tend to sing it rather lower - this is where it's easy to read.
An octave and a third (A to C, where we usually sing it).