Amer Melebari

the idea of the plugin from <a href="http://wpaon.com/?p=48" rel="nofollow ugc">this post</a>
bascally the plugin generats two functions you can use them in your theme
the functions are: 
1. comments_number_ar(‘لا توجد تعليقات’, ‘تعليق واحد’, ‘تعليقان’, ‘% تعليقات’, ‘% تعليق’ ); 
2. comments_popup_link_ar(‘لا توجد تعليقات’, ‘تعليق واحد’, ‘تعليقان’, ‘% تعليقات’, ‘% تعليق’ );
the functions are similar to functions comments_number () and comments_popup_link () 
I just edit them to be correct with Arabic grammare.
<ul>
<li>For more information http://6efy.com/blog/?page_id=2222</li>
</ul>

Arabic Comments Number

this plugin allow you to display the number of comments with Arabic grammar

Jeremy Varnham

This plugin simply replaces Arabic numerals (a.k.a. Hindu-Arabic numerals or Indo-Arabic numerals) with Eastern Arabic numerals (a.k.a. Arabic–Indic numerals or Arabic Eastern numerals) in the date of posts or comments on WordPress. This is useful on sites using the Arabic version of WordPress, which translates month names but leaves the numbers unchanged.

Arabic-Indic Numerals for Arabic WordPress

Replaces "English" numbers with "Arabic" numbers in the Wordpress post date.

Arabic Comments Number vs Arabic-Indic Numerals for Arabic WordPress