Butler says that St. Francis' "intimate friend and great admirer" Bishop Camus writes in his book L'Esprit de St. Francois de Sales that he often often said to Bishop Camus  "That truth must be always charitable; for bitter zeal does harm instead of good.  Reprehensions are a food of hard digestion, and ought to be dressed on a fire of burning charity so well, that all harshness is taken off; otherwise, like unripe fruit, they will only produce gripings.  Charity seeks not itself nor its own interests, but purely the interests of God:  pride, vanity and passion cause bitterness and harshness:  a remedy injudiciously applied may be a poison.  A judicious silence is always better than a truth spoken without charity."   

St Faustina said that sometimes we can give more when we give nothing with charity than we give a lot with an uncharitable spirit.  

St Faustina and Matthew are in agreement.