2 Timothy 2:15
Study .. Give diligence .. "Do your best" The subject matter of "study" here is not the scriptures, but one's self.
The main emphasis is on "rightly dividing the word of truth." = to cut something straight (correctly), to hold a straight course faithfully, (as plowing a straight furrow). The old expositors understood this as a reference to making the proper division between the law and the gospel, between the OT and the NT.