I would like to know how to cite this theorem (which has a quite surprising consequence):

A model category $\mathcal{M}$ is right proper if and only if for any weak equivalence $f:A\to B$, the Quillen adjunction $\Sigma_f:\mathcal{M}/ A \leftrightarrows \mathcal{M} / B:f^*$ is a Quillen equivalence.

I had never heard of it (I never read that in any textbook I believe) before I browse the nLab site which refers to this blog comment from C. Rezk.