\documentclass{minimal}
\usepackage{arabxetex} % default options are "novoc" and "fdf2alif", 
                       % other options are "voc", "fullvoc", "utf", "trans" and "fdf2noalif"
% arabxetex loads bidi.sty and fontspec.sty		       
 
\newfontfamily\arabicfont[Script=Arabic, Scale=1.5]{Scheherazade}
% you can also define \farsifont, \uighurfont, etc if you want
\begin{document}
This is some text in English with Arabic insertion \textarab{`arabI}.

This is some text in English with Arabic insertion \textarab[utf]{عربي}.

This is some text in English with Arabic insertion \textarab[voc]{`arabI}.

\begin{arab}
wa-ha_dihi fiqraT"uN bi-al-`arabiyaT ma`a kalimaT inklIziyaT (\textroman{English}).
\end{arab}

\begin{arab}[utf]
وهذه فقرةٌ بالعربية مع كلمة انكليزية (\textroman{English}).
\end{arab}
\end{document}
