\documentclass[10pt]{article}%,twoside
\usepackage[usenames,dvipsnames]{color}
\usepackage{graphicx}
\usepackage{tikz} 
\usetikzlibrary{positioning,shapes,shadows,arrows}

\usepackage{xepersian}
\settextfont{XB Zar}
\setdigitfont{XB Zar}
\setlatintextfont{Times New Roman}
\begin{document}
\tikzstyle{comment}=[rectangle, draw=black,top color=blue, bottom color=black!20, rounded corners, drop shadow,
        anchor=east, text=white, text width=\textwidth, very thick]

\begin{tikzpicture}[node distance=0cm]
    \node (Rule02) [comment, rectangle split, rectangle split parts=2] {
         \begin{minipage}{1\textwidth}
        \Huge
        قضیه: تعداد اول چند تا است؟
        \end{minipage}
        \nodepart{second}
         \begin{minipage}{1\textwidth}
        بی نهایت اعداد اول وجود دارد 
        
        \end{minipage}
    };
    \end{tikzpicture}
\end{document}