In magnetostatic the continuity equation is: $$\frac {\partial \rho}{\partial t} + \nabla \vec j(\vec r)=0$$. In my script the following is said: Since we are in magnetostatic $\frac {\partial \rho}{\partial t} =0$ and therefore $\nabla \vec j(\vec r)=0$. Now I understand that this $\nabla \vec ...