A Commentary, Critical, Practical, and Explanatory on the Old and New Testaments, by Robert Jamieson, A.R. Fausset and David Brown  at sacred-texts.com
rut 0:0RUTH is properly a supplement to the preceding book, to which, in fact, it was appended in the ancient Jewish canon. Although it relates an episode belonging to the time of the Judges, its precise date is unknown. It appears certain, however, that it could not have been written prior to the time of Samuel (see Rut 4:17-22), who is generally supposed to have been its author; and this opinion, in addition to other reasons on which it rests, is confirmed by Rut 4:7, where it is evident that the history was not compiled till long after the transactions recorded. The inspiration and canonical authority of the book is attested by the fact of Ruth's name being inserted by Matthew in the Saviour's genealogy [Mat 1:5].