Answer:
   
   The question raised concerning the incident in the Book of Ruth 4:7 is
   an interesting one. This practice was formerly done in Israel in cases
   of redemption or exchange: to validate any transaction, one man would
   take off his sandal and hand it to the other. Apparently this was an
   early form of acquisition (kinyan) where the sign of agreement was
   made by the passing or transfer of an inanimate object. In some cases
   that was a shoe, a scarf, etc. The author of Ruth is describing this
   practice while seeming to suggest it is no longer the case.
   
   However we know that among Jews this practice or a form of it
   continued. The Talmud, the work of the rabbis, is filled with such
   examples. In the tractate Baba Mezia (46a) a transaction takes place
   in a granary through a scarf. This is in lieu of one who left his
   money at home! Even in our own day, the agreement made before a
   wedding (Tenaim) and a symbol of the agreement made in the document of
   betrothal is formalized by a "symbolic delivery" by, according to the
   Orthodox Rabbis' Manual, HAMADRIKH, "...letting the parties concerned
   hold a kerchief, that they will fulfill whatever is provided for in
   the tenaim." Here we see that an ancient custom continues in some form
   today. Such a practice can also be found in other cultures as well.
   The Rev Dr A. Cohen in his commentary on Ruth (Soncino Press)
   suggests, "The custom is also known among the Indians, the ancient
   Germans and the Arabs." Without trying to confuse the issue, the
   particular sandal practice has also been linked to the law in
   Deuteronomy 25:5. This is the obligation of a brother (Levir) to marry
   the wife of his deceased sibling. According to Deuteronomy, should he
   refuse, he is to go to the gate of the city and there the widow is to
   "pull off the sandal, spit in his face..."
   
   In Ruth, the rejecting kinsman is not a brother-in-law to Ruth, but he
   is described as her "redeemer." While most commentators reject the
   connection, it is unavoidable.