\documentclass{article} 
\usepackage{amsmath,amssymb}

\usepackage{xepersian}
\setdigitfont{XB Zar}
\begin{document}
\begin{align*} 
3&\nmid\gamma\\ 
3&\nmid x\gamma y\\
3& \nmid\gamma
\end{align*}
\end{document}