The Buddha had some very specific, original teachings on karma that have much relevance to the meditation.
"We don’t often think of the teachings on karma as having much relevance to the meditation. Sometimes we’re even taught that karma was one of those weird pieces of cultural baggage that somehow got smuggled into Buddhism from its cultural background. But that’s not the case at all. The Buddha had some very specific teachings on karma that had nothing to do with what anybody else was teaching at the time, and they’re immediately relevant to why and how we’re meditating. The “why” has to do with the point I just raised. Given that karma is intention, and intention is the huge shaping force in your life, you want some control over it. If you make up your mind to do something that you know is good, you want to be able to stick with that intention. And where does intention happen? Right in the present moment. Where does it get changed? In the present moment. This is why we focus on the present moment, so that we can see the process of intention in action as it happens and...