A.T. Robertson Commentary Matthew 18:7

"Woe unto the world because of occasions of stumbling! for it must needs be that the occasions come; but woe to that man through whom the occasion cometh!" — Matthew 18:7 (ASV)

Through whom (δι' ου). Jesus recognizes the inevitableness of stumbling-blocks, traps, hindrances, the world being as it is, but he does not absolve the man who sets the trap (cf. Luke 17:1).