'Certain' in the Bible

Now it came to pass in the days when the judges ruled, that there was a famine in the land. And a certain man of Bethlehemjudah went to sojourn in the country of Moab, he, and his wife, and his two sons.

Now, in earlier times this was the way in Israel when property was taken over by a near relation, or when there was a change of owner. To make the exchange certain one man took off his shoe and gave it to the other; and this was a witness in Israel.