var totalNToReplace = 3;

jQuery().ready(function(e) {


	jQuery('p').replaceFirstNWith(/\bahmad\b/i, "<a class='smartlinks' href='test' title='ahmad' target='_self'>ahmad</a>", '1');

});

// Following function slightly modified from: https://codereview.stackexchange.com/questions/14010/replacing-the-first-n-occurrences-of-a-term
jQuery.fn.replaceFirstNWith = function(yourregex, replacetext, firstNToReplace) {
	var regexp, flags = "g";

	// Allow user to pass a RegExp object instead of a string.
	if( yourregex instanceof RegExp ) {
		// No way to set the global flag on an existing regexp object,
		// so "copy" it by checking flags, and extracting the source
		if( yourregex.ignoreCase ) flags += "i";
		if( yourregex.multiline ) flags += "m";
		yourregex = yourregex.source;
	}
	regexp = new RegExp(yourregex, flags); // build the regexp
	jQuery(this).each(function (index, value) {

		if( firstNToReplace < 0 ) return; // skip if enough replacements have been made already
		if( totalNToReplace < 0 ) return; // skip if enough total replacements have been made already
		
		var html = jQuery(this).html().replace(regexp, function () {
			if( --firstNToReplace < 0 || --totalNToReplace < 0 ) { // decrement count and check
				return arguments[0]; // return the matched string with no changes
			}
			return replacetext;
		});
		jQuery(this).html(html);
	});
}