Depend upon it, there is always a cause for want of appetite; […] inflammation may be in the system, food would then be improper, as it would only add fuel to fire: therefore, let the cause be an over-worked stomach, overloaded bowels, fever, or inflammation, food will be injurious.
1867 October,“‘Our Van.’ The Invoice.—September Scrapings.”, inBaily's Magazine of Sports and Pastimes, volume XIV, number 92, London: A. H. Baily & Co., Cornhill, page 50:
We have no wish to add fuel to fire, and perhaps the whole circumstance of Pastorelle cutting such a very different figure to what she did on the first day was purely accidental.
Quotations
For more examples of usage of this term, see Citations:add fuel to fire.