The hardness may be in the use of hurting words.

It may be in the form of ascribing very bad attributes to the condemned person or uttering such accusations that prejudice his honor, his character, or his mentality. For example the words “you fool” are hurting words which should be punished by hell fire as the Lord said (Mt. 5: 22). How many, actually, are the words and expressions used by people bearing the same meaning of “you fool”.

Judge Not Others
H.H. Pope Shenouda III