Sayyiduna Abu Ayyub al-Ansari (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) used to pray four rak'ahs after the sun passed its zenith. Sayyiduna Abu Ayyub (may Allah be pleased with him) said: O Messenger of Allah, what is this prayer? He (peace and blessings be upon him) said: "The gates of heaven are opened when the sun passes its zenith, and the gates of heaven are not closed until the Zuhr prayer. I love that my good deeds ascend before the gates of heaven are closed." I asked: O Messenger of Allah, do you (peace and blessings be upon him) recite in them? He (peace and blessings be upon him) said: "Yes, I recite in all of them." The narrator said: Are they separated by a salam? He (peace and blessings be upon him) said: "No, the salam is only in the last rak'ah."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4579
Sayyiduna Abu Ayyub al-Ansari (may Allah be pleased with him) said that the Prophet (peace and blessings be upon him) would always pray four rak'ahs in my house after the sun passed its zenith. I said: O Messenger of Allah, what is this prayer that you pray? Then he mentioned the hadith in the same way.
Ubaydah bin Mu'attib is da'if (weak); his report is not taken as proof. Abu Dawud said: Ubaydah is da'if (weak). It has also been narrated from Abu Ayyub through another chain that is not strong.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4580
Sayyiduna Abu Ayyub (may Allah be pleased with him) said that the Prophet (peace and blessings be upon him) used to pray four rak'ahs before Zuhr. It was said to him (peace and blessings be upon him): "Do you keep up this prayer constantly?" He (peace and blessings be upon him) said: "When the sun passes its zenith, the gates of heaven are opened, and I love that my deeds go up before the gates of heaven are closed."
(b) The established (authentic) hadith has come permitting five rak'ahs in witr, with no tashahhud and no salam between them except in the last of them; and permitting nine, sitting only in the eighth and saying the salam only in the ninth. That too is mentioned in (the chapter of) witr.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4581