The Prophet (ﷺ) asked AbuBakr: When do you observe the witr?

He replied: I observe the witr prayer in the early hours of the night.

The Prophet (ﷺ) asked Umar: When do you observe the witr?

He replied: At the end of the night.

He then said to AbuBakr: This has followed it with care; and he said to Umar: He has followed it with strength.
Sunan Abi Dawud Book 8, Hadith 19
← Previous Hadith My friend (i.e. the Prophet) instructed me to observe three practices which I never leave: he instructed me to fast three days every month, and not to sleep but after observing the witr, and to observe supererogatory prayer in the forenoon while traveling and while resident.

Sunan Abi Dawud Book 8, Hadith 18 Next Hadith → I asked 'Aishah: When would the Messenger of Allah (ﷺ) observe the witr prayer ? She replied: Any time he observed the witr, sometimes in the early hours of the night, sometimes at midnight and sometimes towards the end of it. But he used to observe the witr just before the dawn when he died.

Sunan Abi Dawud Book 8, Hadith 20