Muslim

Hadith Commentary:
(1)
Regarding the prayer of Umar ibn Abd al-Aziz rahimahullah, Anas radi Allahu anhu commented in these words: “I have not seen anyone whose prayer more closely resembled the prayer of the Messenger of Allah sallallahu alayhi wa sallam than this young man, i.e., Umar ibn Abd al-Aziz rahimahullah.”
(Musnad Ahmad: 2/329, 330)
The incident mentioned in the hadith is from before he became caliph, because during the time of Anas radi Allahu anhu, he was the governor of Madinah on behalf of Walid ibn Abd al-Malik, and Anas radi Allahu anhu passed away before Umar ibn Abd al-Aziz rahimahullah became caliph.
It is possible that Umar ibn Abd al-Aziz rahimahullah delayed the Zuhr prayer due to some excuse.
It is also possible that this delay occurred in accordance with the custom of the Umayyad rulers, as the rulers of Banu Umayyah had become accustomed to performing the prayers late. However, considering Umar ibn Abd al-Aziz rahimahullah’s zeal for following the Sunnah, the first reason is more likely.
And Allah knows best.

(2)
From the aforementioned narration, it is understood that immediately after performing the Zuhr prayer with Umar ibn Abd al-Aziz rahimahullah, Anas radi Allahu anhu performed the Asr prayer. This shows that he performed the Asr prayer at its earliest time.
And this is the intended point. This detail is also evident from another narration:
Ala’ ibn Abd al-Rahman says that after finishing the Zuhr prayer, we went to visit Anas radi Allahu anhu at his residence.
At that time, he was residing in Basrah, and his house was in front of the mosque.
When we went to him, he said:
“Have you performed the Asr prayer?” We replied:
“We have just come after finishing the Zuhr prayer.”
He said:
“Alright, now perform the Asr prayer.” So we performed the Asr prayer.
Then he said:
“I heard the Messenger of Allah sallallahu alayhi wa sallam say: ‘This is the prayer of the hypocrite: he sits waiting for the sun, and when it comes between the two horns of the Shaytan, he stands and pecks out four (rak‘ahs) quickly, in which he barely remembers Allah.’”
(Sahih Muslim, Kitab al-Salat, Hadith: 1412(622))

(3)
The following narration is also clear regarding the time of the Asr prayer.
Anas radi Allahu anhu narrates that one day the Messenger of Allah sallallahu alayhi wa sallam led us in the Asr prayer. After finishing the prayer, a man from the tribe of Banu Salamah came to him and said that they had planned to slaughter a camel and wished for the Prophet sallallahu alayhi wa sallam to join them. So we went there with the Messenger of Allah sallallahu alayhi wa sallam, and the camel had not yet been slaughtered. After that, it was slaughtered, its meat was cut and cooked, and we ate it before the sun had set.
(Sahih Muslim, Kitab al-Salat, Hadith: 1414(624))
It should be noted that the houses of the tribe of Banu Salamah were very far from the Prophet’s Mosque.
Once, they expressed the desire to move closer to the Prophet’s Mosque, but the Messenger of Allah sallallahu alayhi wa sallam stopped them and said that the farther a person walks to the prayer, the greater the reward he receives.
(Sahih al-Bukhari, Kitab al-Adhan, Hadith: 656)

510. Commentary: The Umayyad caliphs would generally perform the Zuhr (noon) prayer late, to the extent that its final time would approach. At the time of this incident, Umar ibn Abd al-Aziz rahimahullah was the governor of Madinah Munawwarah. In following the caliphs, he too would delay the prayer. When he was informed that the Messenger of Allah sallallahu alayhi wa sallam used to perform the prayer early, he abandoned the practice of delaying it.

511. Commentary: From all these narrations, it is explicitly understood that the Messenger of Allah (sallallahu alayhi wa sallam) used to perform the ‘Asr prayer as soon as its time began. And this is the Sunnah. Although performing the prayer before the sun turns yellow is permissible without dislike, it is not preferable. Therefore, the ‘Asr prayer should be performed at its earliest time. If, due to some engagement, it is occasionally delayed, there is no harm. And Allah knows best.