Sayyidah Aishah Siddiqah (may Allah be pleased with her) narrates: The Prophet (peace and blessings be upon him) would pray in the chamber while I was in the house, and the Prophet (peace and blessings be upon him) would separate the even rak'ahs from the witr with a salam, and he would let us hear that salam (that is, he would say the salam aloud).
Imam Ahmad recorded this narration; Umar bin Abd al-Aziz did not live in the time of Sayyidah Aishah (may Allah be pleased with her).
Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) narrates: The Prophet (peace and blessings be upon him) would separate the even prayer from the witr by saying the salam aloud.
Imam al-Tabarani recorded this narration in al-Mu'jam al-Awsat; its chain contains a narrator, Ibrahim bin Sa'id, who is da'if (weak).