Al-Aswad bin Hilal narrates: I bear witness concerning Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) that I heard him calling out loudly, saying: The witr is to be performed between two prayers, the Isha prayer, which you call 'Atamah', and the Fajr prayer; whenever you perform the witr (between these two prayers), it is good.
Imam al-Tabarani recorded this narration in al-Mu'jam al-Kabir, and its narrators are the narrators of the Sahih.