Sunan Abi Dawud Book 5, Hadith 76
The Prophet (ﷺ) was asked: which is the best action? He replied: To stand in prayer for a long time.
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.
A man asked the Messenger of Allah (ﷺ) about the prayer at night. The Messenger of Allah (ﷺ) said: Prayer during the night should consist of pairs of rak'ahs, but if one of you fears the morning is near he should pray one rak'ah which will make his prayer an odd number for him.