How to prove without using of advanced theorems that quaternions algebra $H = \left(\frac{-1,-1}{\mathbb{Zp}} \right)$,where p - is prime that H $\cong$ $Mat_2({\mathbb{Zp}})$

My ideas: I tried to build an explicit isomorphism, but as I think it is only possible when p = 1 (mod 4), and for p = 1 (mod 4) it get it. In my second attempt, I tried to look at them as vector spaces of the same dimension.