$re = '/((?:(?!((\sincoming|outgoing)\smessage)).)*keyword.*?)((incoming|outgoing)\smessage)/i';
$str = 'Incoming message Incoming message Incoming message keyword abctext keyword Incoming message Incoming message gsgsfvhvhgh gfvgvhhhjjbn 765568856866
Incoming message outgoing message Incoming message 91981966802866 keyword other text Dhai 20-12-2017 15:29:47 Text Incoming message';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php