Sunan Abi Dawud Book 5, Hadith 75

He should then prolong it afterwards as much as he likes.

Abu Dawud said: This tradition has been transmitted by Hammad b. Salamah, Zuhair b. Mu'awiyah and a group of narrators from Hisham. They transmitted it as a statement of Abu Hurairah himself (mauquf).

This tradition has also been transmitted by Ibn 'Awn from Muhammad (b. Sirin). This version has the wordings: These two rak'ahs were short.