What is the ruling on commenting with: "He was silent for a long time and then spoke blasphemy," regarding the words of a person who was silent for a long time and then uttered bad words, knowing that the commentator does not intend for this statement to be disbelief (kufr) nor does he believe its speaker to be a disbeliever (kafir)?

There is no harm in using the phrase "in sha' Allah" (God willing) as a proverb that has become proverbial, and whose intended meaning has become general, contrary to what its literal wording denotes. A proverb is transferred from its literal meaning to a more general meaning. However, avoiding its use might be more appropriate and better due to the ambiguity it entails.