Does a traveler who prayed 'Isha and stood for the third rak'ah, then completed it, have to perform the prostration of forgetfulness (sujud al-ba'di)?

If a traveler, for whom shortening the prayer is legislated, prays three rak'ahs for 'Isha' prayer by mistake, he must perform the prostration of forgetfulness (sujud al-sahw) after the tasleem. It is also permissible for him to prostrate before the tasleem.