The word certain, when applied to man, hath a very special and particular meaning. It is not unlike, for importance, the phrase of a man of God, to distinguish from a man of the world; or the natural man, to distinguish from the spiritual and the inward man of the heart, to denote somewhat from that which is merely outward. So, in like manner, when in Scripture, at any time, it is said, a certain man, there is somewhat striking affixed to the expression; such as in that instance, when It is said, a certain man drew a bow at a venture, and smote the king, (1 Kings 22:34) the meaning is the arrow was directed by the Lord. So again, when it is said in the gospel, a certain man had two sons, (Luke 15:11) a Certain man had a fig tree planted in his vineyard, (Luke 13:6) a certain man made a great supper, and bade many, (Luke 14:6) all these, and the like, directly refer to the Lord. So again, when it is said, (as in Ruth 1:1-22) a certain man of Bethlehem-judah went to sojourn in the country of Moab. And again, in the gospel, (Luke 10:30) a certain man went down from Jerusalem to Jericho, and fell among thieves. Both these cases, as well as others of a similar kind, are designed to represent our nature universally. All men, from our first father, have left Bethlehem-judah, the land of bread, for so the name means; and Jerusalem, the holy city; and by going down to the Moabs and the Jerichos of the world, have fallen among thieves, and been left more than half dead by the great enemy of souls.

Bibliography Information
Hawker, Robert D.D. Entry for 'Certain'. Hawker's Poor Man's Concordance and Dictionary. https://www.studylight.org/dictionaries/eng/pmd/c/certain.html. London. 1828.

Bible Dictionaries Certain

Hawker's Poor Man's Concordance And Dictionary

Bible Dictionaries
Certain