Words not Cast Aside (捨てられねェ言葉, Suterarenee Kotoba) is chapter 543 of the Naruto manga.
The Raikage tells Minato to save his nonsense, and runs in to attack. Minato moves to stab B, but B too has a blade pointing at Minato. Minato states that he's taken a liking to B. In the present, Naruto moves to attack the Raikage, but misses. B and A trade blows, and B attempts to use the Lariat against his brother, who claims that B's Lariat is inferior to his own. The Raikage calls for Tsunade's aid, instead, she moves to stand in front of Naruto and B, remembering Naruto's promise that he wouldn't die until he became the Hokage, arguing that were Naruto to die, the next jinchūriki wouldn't be able to control the Nine-Tails as well as Naruto can. The Raikage asks what guarantee they have that Naruto will succeed. B again tries his Lariat against the Raikage. The brothers recall the time the Third Raikage passed away, when A told B that he didn't need to use the Lariat anymore, that he should focus solely on improving his Tailed Beast Ball and that he was forbidden to leave the village. Again, A and B clash with their Lariat, with B's proving the strongest, much to A's dismay. B proceeds to tell him that his and Naruto's power doesn't come from being jinchūriki, and that his brother's words long ago gave him the strength to surpass him.