Narrated Ibn Shihab (R.a):
Once `Umar bin `Abdul `Aziz (r.a) delayed the prayer and `Urwa bin Az-Zubair (r.a) went to him and said, “Once in ‘Iraq, Al-Mughira bin Shu`ba delayed his prayers and Abi Mas`ud Al-Ansari went to him and said, ‘O Mughira! What is this? Don’t you know that once Gabriel came and offered the prayer (Fajr prayer) and Allah’s Messenger prayed too, then he prayed again (Zuhr prayer) and so did Allah’s Apostle and again he prayed (`Asr prayers and Allah’s Messenger did the same; again he prayed (Maghrib-prayer) and so did Allah’s Messenger and again prayed (`Isha prayer) and so did Allah’s Apostle and (Gabriel) said, ‘I was ordered to do so (to demonstrate the prayers prescribed to you)?’” `Umar (bin `Abdul `Aziz) said to `Urwa, “Be sure of what you Say. Did Gabriel lead Allah’s Messenger at the stated times of the prayers?” `Urwa replied, “Bashir bin Abi Mas`ud narrated like this on the authority of his father.” `Urwa added, “Aisha told me that Allah’s Messenger used to pray `Asr prayer when the sunshine was still inside her residence (during the early time of `Asr).

Reference : Sahih al-Bukhari 521, 522
In-book reference : Book 9, Hadith 1
USC-MSA web (English) reference : Vol. 1, Book 10, Hadith 500