Adam Clarke on Matthew 18:7

Wo! - Or, alas! ουαι. It is the opinion of some eminent critics, that this word is ever used by our Lord to express sympathy and concern.

Because of offenses - Scandals, stumbling-blocks, persecutions, etc.

For it must needs be that offenses come - Αναγκε γαρ εϚιν ελθειν τα σκανδαλα, for the coming of offenses is unavoidable. Such is the wickedness of men, such their obstinacy, that they will not come unto Christ that they may have life, but desperately continue deceiving and being deceived. In such a state of things, offenses, stumbling-blocks, persecutions, etc., are unavoidable.

Wo to that man - He who gives the offense, and he who receives it, are both exposed to ruin.