How do I prove the following by integration by parts:
$$\iiint \left( \vec{\triangledown} . \dfrac{\vec{I}}{r} \right)dV=\iint\dfrac{1}{r} \vec{I}.\hat{n} dS-\iiint\dfrac{1}{r} \left( \vec{\triangledown} . \vec{I} \right)dV$$
given that:
$$\vec{\triangledown}.\left( \dfrac{\vec{I}}{r}\right)=\vec{\triangledown}\dfrac{1}{r} . \vec{I} + \dfrac{1}{r} \vec{\triangledown}.\vec{I}$$