To show that it is not true (note that the Laplacian has to be taken component wise for this question to even make sense), take a look at the vector field
$$\vec{u}(x,y,z)= \begin{pmatrix} y^2\\0\\0 \end{pmatrix}$$
and show that the divergence vanishes but the Laplacian does not.
To show that it is not true (note that the Laplacian has to be taken component wise for this question to even make sense), take a look at the vector field $$\vec{u}(x,y,z)= \begin{pmatrix} y^2\\0\\0 \end{pmatrix}$$ and show that the divergence vanishes but the Laplacian does not.