One of the first things I learned about Baroque vocal music is that a recitative is ‘always’ followed by an aria for the same singer. (The older me, as a teacher, spent several decades preaching that the words ‘always’ and ‘never’ are hardly ever true in this kind of context!) So I was rather baffled when, on encountering Messiah for the first time during my A-level years, I noticed that early in the work the recitative for bass ‘Thus saith the Lord’ was followed by an aria for alto ‘But who may abide’.
The explanation, I eventually discovered, lies in the work’s compositional and performance history. Handel never actually performed Messiah exactly as he wrote it and his first setting of ‘But who may abide’ for bass (as it ‘should’ have been) was one of the sections that went unheard. He did, however, make use of a revised version for bass, before embarking on the comprehensive re-think that produced the brilliant alto version, for a specific star soloist, that we now most commonly hear. Handel subsequently made two different adaptations of this for soprano and there is also a setting of this text as a recitative (for bass). But that may have written by someone else . . .