Answer

Where is reward and punishment written in the Torah?
As for the justice issue, I don’t know. That is one of the considerations that leads to the conclusion that there is a World to Come. But that itself makes me suspicious that this concept was invented by the Sages and was not received as part of the tradition from Sinai (precisely because it is needed and makes sense). And if that is indeed so, then maybe it makes sense to think that there is a World to Come, but it is not necessary. There could perhaps be other solutions to divine justice (reincarnations, or simply something we haven’t thought of). Rational conclusions—not in the sense of logic but of philosophy—are limited by their very nature. That is why specifically beliefs that make sense arouse my suspicion, and I do not reach a high degree of certainty about them.