Be ye therefore very courageous to keep and to do all that is
 written in the book of the law of Moses
 To observe which required spiritual strength, fortitude of mind, a holy courage, a firm and fixed resolution, and particularly to destroy the Canaanites required in that book, and to abstain from all communion and fellowship with them: 
 that ye turn not aside therefrom, [to] the right hand or the left;
 (See Gill on Joshua 1:7).