Hadith 507540
Chapter 20: Hajj - كتاب الحج
وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ يَحْيَى بْنِ سَعِيدٍ، أَنَّ عُمَرَ بْنَ عَبْدِ الْعَزِيزِ، غَدَا يَوْمَ عَرَفَةَ مِنْ مِنًى فَسَمِعَ التَّكْبِيرَ عَالِيًا فَبَعَثَ الْحَرَسَ يَصِيحُونَ فِي النَّاسِ أَيُّهَا النَّاسُ إِنَّهَا التَّلْبِيَةُ .
Yahya related to me from Malik, from Yahya ibn Said, that Umar ibn Abd alAziz was once going from Mina (to Arafa) on the day of Arafa and heard the takbir being said loudly, so he sent the guard to shout out to the people, "O people, you should be saying the talbiya."
Reference Muwatta Malik 507540
USC-MSA web (English) reference : Book 20, Hadith 49