As it happened, as soon as he had turned his back to leave Sh’mu’el, G-d gave him another heart; and all those signs took place that day.
I find it curious that in the last chapter, Sh’mu’el told Shau’ul about the things that were on his heart and then in this chapter his heart is changed. It felt to me like that could have been more of a neutral statement, though there could be a nuanced angle revealing that Sha’ul harbored some negativity. It is unclear to me, but I think the point was to state that Sha’ul believed Sh’mu’el because he knew of things that he had kept only in his heart. Why did his heart need to change? Was there something fundamentally wrong with it? Given his future, does his heart change back to what it had been? How does that happen? Did the Father let it? Cause it? While there is foreboding given the choices Sha’ul makes later on, there is a glimmer of hope here. If Our Heavenly Father can give someone a new heart, then we can pray that He do the same for us, that we may love Him and our neighbors as we should.