Abu Hurayrah (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) led us in Zuhr or Asr and gave the salam after two rak'ahs, so Dhu al-Yadayn (may Allah be pleased with him) said: O Messenger of Allah, has the prayer been shortened, or have you forgotten? The Messenger of Allah (peace and blessings be upon him) asked his Companions: "Is Dhu al-Yadayn (may Allah be pleased with him) telling the truth?" They said: Yes. So he (peace and blessings be upon him) led the other two rak'ahs and then performed the two prostrations of forgetfulness.
Shu'bah (may Allah have mercy on him) narrates that Sa'd (may Allah have mercy on him) said: I saw Urwah bin al-Zubayr (may Allah have mercy on him) give the salam after leading two rak'ahs of the Maghrib prayer and then speak; after that he prayed the rest of the prayer and said: This is how the Messenger of Allah (peace and blessings be upon him) did it too.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3906