# even if I exult in pain that does not lessen

"I would leap for joy in unending pain" or "I would endure pain that does not diminish"

# exult

"rejoice"

# does not lessen

"does not diminish"

# that I have not denied the words of the Holy One

"that I have not disowned God." This can be written in positive form. Alternate translation: "that I have always obeyed the Holy One"