The expression "righteousness is immortal" obliges to think. There is no need to say that lie leads to death, and of course above all to the spiritual death, here everything is more or less clear. But here is, with the immortality of righteousness everything is not clear.
What stands behind it? Does the immortality of righteousness mean the immortality of the righteous? Or it is only about the sustainability of the Torah, about the immutability of the commandments given by God? And may be, both? Certainly, the sustainability in itself of any principle doesn’t suppose at all the immortality of the one who follows this principle. But can we consider righteousness as being only a principle?
Formally yes, because it is about commandments given by God, some kind of moral code, as some people believe. But, even if we read attentively the Decalogue, distracting for a certain time of all the other traditions, it would be easy to notice that it is not simply a matter of moral norms, but of two ways, which one leads to God and another withdraws from God.
And generally, we can hardly considerer righteousness as only a principle. Because after all, only God can be considered as the source of every righteousness, and only He is righteous in all the sense of this word. And if that is the case, then every human justice by definition is inseparable from relationships with God, His plan, His Kingdom.
But there is it a place for death in the Kingdom? If not, then each, implied in righteousness, and thus, implied in the Kingdom, sooner or later will find the plenitude of an appropriate life for the Kingdom. And will become a living incarnation of God’s righteousness.