Kidneys or Emotions?
In ancient times, people had a primitive understanding of the human body. The kidneys were considered to be the seat of emotions, so many references to the kidneys are found in ancient texts which are actually referring to deeply-felt emotions.
So instead of saying ‘kidneys’ literally, which sounds very weird to modern readers, we translate it to say what it really meant, ‘emotions’ or similar phrases.
Of course, we only do this when the context is speaking about the kidneys in that way, not when literally talking about the kidneys, like when talking about animal sacrifices.