Sayyiduna Abu Sa'id al-Khudri (may Allah be pleased with him) narrates: It was said: "O Messenger of Allah! May the Witr be prayed after the adhan of Fajr?" the Prophet (peace and blessings be upon him) said: "Pray the Witr before the adhan." The narrator says: In the time of the Prophet (peace and blessings be upon him) the adhan was given after the true dawn had broken. The people said: "May the Witr be prayed after the adhan?" the Prophet (peace and blessings be upon him) said: "Pray the Witr before the adhan." The people asked a third time: "May the Witr be prayed after the adhan?" the Prophet (peace and blessings be upon him) said: "Pray the Witr after the adhan." (The narrator says:) the Prophet (peace and blessings be upon him) granted them a concession. (Allamah al-Haythami says:) I say: Abu Dawud recorded a hadith from Sayyiduna Abu Sa'id al-Khudri (may Allah be pleased with him) about making up the Witr, but it is other than this hadith.
Al-Tabarani recorded it in al-Mu'jam al-Awsat; its chain contains Yusuf bin Khalid al-Samti, who is da'if (weak).