Rothbard believes it emanates from the fact that we have an innate ownership of ourselves (self-ownership). From this, Rothbard derives much of his ethical framework. This is used to argue that property rights are the core of all human rights. But I think it's an wholly unconvincing moral epistemology, that is essentially a category mistake at its core.
Discussion
Many in the bitcoin world discover Rothbard and then believe they've stumbled upon a beautiful, self-consistent moral truth that, if followed, can fix most of what's wrong with the world. In reality, it's a silly utopian fantasy that is likely to come falling down quickly if you spend much time getting into the deeper issues of moral epistemology, brought up most notably by David Hume, which Rothbard quickly dispenses with in an almost neo-Aristotelean protest against the claims that all ethics must necessarily be subjective. Rothbard's contemporary, Hoppe, tries to put a lid on this contradiction with his "argumentation ethics" as well. But it's all resting on pretty messy metaphysics and epistemology.
My pet peeve has become bitcoiners trying to school me in Rothbardian ethics several times a week, like I've never been enlightened by its captivating and self-evident truths. 🤣