Bruce R. McConkie
"Boasting in the arm of flesh, one of the commonest of all sins among worldly people, is a gross evil; it is a sin born of pride, a sin that creates a frame of mind which keeps men from turning to the Lord and accepting his saving grace. When a man engages in self exultation because of his riches, his political power, his worldly learning, his physical prowess, his business acumen, or even his works of righteousness, he is not in tune with the Spirit of the Lord. Salvation itself comes by the grace of God, 'Not of works,' that is not of the performances and outward display of the law, 'lest any man should boast.' (Eph. 2:4-22; Rom. 3:27.) As King Benjamin asked, after explaining the goodness of God and the comparative nothingness of men, 'Of what have ye to boast?' (Mosiah 2: 17-26.)" (Mormon Doctrine, p. 93)