Musnad Ahmad 482:39

Ya'qub narrated to us, he said: My father narrated to us, from Ibn Ishaq, he said: Yazid ibn Abi Habib al-Misri narrated to me, from Marthad ibn Abdullah al-Yazani—and Yazan is a sub-tribe of Himyar—he said: Abu Ayyub Khalid ibn Zayd al-Ansari, the companion of the Messenger of Allah (may Allah bless him and grant him peace), came to us in Egypt as a warrior—and Uqbah ibn Amir ibn Abs al-Juhani had been appointed over us by Mu'awiyah ibn Abi Sufyan. He said: Uqbah ibn Amir delayed the Maghrib prayer. When he prayed, Abu Ayyub al-Ansari stood up to him and said to him: "O Uqbah, is this how you saw the Messenger of Allah (may Allah bless him and grant him peace) pray Maghrib? Did you not hear the Messenger of Allah (may Allah bless him and grant him peace) say: 'My nation will continue to be in goodness—or upon the natural disposition (fitrah)—as long as they do not delay Maghrib until the stars become intertwined'?" He said: He replied, "Yes." He said: "Then what compelled you to do what you did?" He said: "I was occupied." Abu Ayyub said: "By Allah, I have no concern except that people might think that you saw the Messenger of Allah (may Allah bless him and grant him peace) doing this."