I will open my mouth in a parable - See the notes at Psalms 49:4. The word “parable” here means a statement by analogy or comparison; that is, he would bring out what he had to say by a course of reasoning founded on an analogy drawn from the ancient history of the people.
I will utter dark sayings of old - Of ancient times; that is, maxims, or sententious thoughts, which had come down from past times, and which embodied the results of ancient observation and reflection. Compare Psalms 49:4, where the word rendered “dark sayings” is explained. He would bring out, and apply, to the present case, the maxims of ancient wisdom.