function limitWords($str,$limit){
	$wc 	= explode(' ',$str);
	$c 	= count($wc);
	$r = '';
	if($c <= $limit)
		$r = $str;
	else{
		$i=0;
		while($i<$limit){
			$r .= $wc[$i].' ';
			$i++;
		}
	}
	return $r;
}

function limitWords($str,$limit){
	$wordCount 	= explode(' ',$str);
	$count 		= count($wordCount);
	$return 	= '';
	if($count <= $limit)
		$return = $str;
	else{
		$i=0;
		while($i<$limit){
			$return .= $wordCount[$i].' ';
			$i++;
		}
	}
	return $return;
}

Example:

echo limitWords('This is my string personally i think its too long',2);

Will return "This is"

PHP Limit Words

PHP