Understanding $SL_3(D)$ where D is a central division algebra

Question

Suppose that $K$ is a non-archimedean local field of positive characteristic and $D$ is a four-dimensional central division algebra over $K$. The group $SL_{3}(D)$ can be embedded as a $K$-form of $SL_{6}(K')$ for some finite Galois extension $K'$ of $K$. Would there be anywhere where I could read more about exactly how this works, as in some kind of description of what the embedding is?