(89) باب الْجَمْعِ بَيْنَ الصَّلاَتَيْنِ بِعَرَفَةَ
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?"
Reference: Sahih al-Bukhari 1662
In-book reference: Book 25, Hadith 143
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 2, Book 26, Hadith 724