One of the things about Blind Willie Johnson's "Dark Was the Night" that is mysterious is exactly which tune he was extrapolating his performance from. The text of "Dark Was the Night and Cold the Ground" is relatively well-known. We can establish that it's credited to Thomas Hawells.
The text is listed as follows:
1 Dark was the night, and cold the ground
On which the Lord was laid;
His sweat like drops of blood ran down;
In agony He prayed.
2 "Father, remove this bitter cup,
If such Thy sacred will;
If not, content to drink it up
Thy pleasure I fulfill."
3 Go the the garden, sinner, see
Those precious drops that flow;
The heavy load He bore for thee;
For thee He lies so low.
4 Then learn of Him the cross to bear;
Thy Father's will obey;
And when temptations press thee near,
Awake to watch and pray.
So if you want to understand what Blind Willie Johnson was adapting into music you'll have to know the text he was working from even if he never sang the words. Mahalia Jackson, by contrast, did sing the words and it helps us get a clearer sense of how flexible this text has been in terms of melodic settings. The hymn is also mentioned as being in an African Methodist Episcopal hymnal.
