Sahih Muslim 1766
صحيح مسلم#1766SahihJabir reported Allah's Messenger (ﷺ) as saying:If anyone is afraid that he may not get up in the latter part of the night, he should observe Witr in the first part of it; and if anyone is eager to get up in the last part of it, he should observe Witr at the end of the night, for prayer at the end of the night is witnessed (by the angels) and that is preferable
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih Muslim is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 6:195