Ibn Shihab said

Salim said, "In the year when Al-Hajjaj bin Yusuf attacked Ibn Az-Zubair, the former asked 'Abdullah (Ibn 'Umar) what to do during the stay on the Day of 'Arafa (9th of Dhul-Hajjah). I said to him, "If you want to follow the Sunna (the legal way of the Prophet (ﷺ)) you should offer the Salat just after midday on the Day of the 'Arafa. 'Abdullah bin 'Umar said, 'He (Salim) has spoken the truth.' " They (the Companions of the Prophet (ﷺ)) used to offer the Zuhr and Asr prayer together according to the Sunna, I asked Salim, "Did Allah's Messenger (ﷺ) do that ?" Salim said, "And in doing that do you (people) follow anything else except his (ﷺ) Sunna?"