A little logic:

Temptation = Consequence (or else it wouldn't be temptation, just a decision)

Consequence = Punishment (Just another fancy word)

Punishment = Outcome of negative action (if it wasn't it would be a reward)

Outcome of negative action = Negative action was taken (Can't get anymore obvious then that)

Negative Action was taken = Sin

Temptation = Consequence = Punishment = Outcome of negative action = Negative action was taken = Sin

Therefore: Temptation = Sin