Language:
كتاب الحج
25  
Hajj (Pilgrimage)
(134)
Chapter: To do the Rami of the Jimar
(134)
باب رَمْىِ الْجِمَارِ
Sahih al-Bukhari 1746

Narrated Wabra:

I asked Ibn `Umar, "When should I do the Rami of the Jimar?" He replied, "When your leader does that." I asked him again the same question. He replied, "We used to wait till the sun declined and then we would do the Rami (i.e. on the 11th and 12th of Dhul-Hijja)."

حَدَّثَنَا أَبُو نُعَيْمٍ، حَدَّثَنَا مِسْعَرٌ، عَنْ وَبَرَةَ، قَالَ سَأَلْتُ ابْنَ عُمَرَ ـ رضى الله عنهما ـ مَتَى أَرْمِي الْجِمَارَ قَالَ إِذَا رَمَى إِمَامُكَ فَارْمِهْ‏.‏ فَأَعَدْتُ عَلَيْهِ الْمَسْأَلَةَ، قَالَ كُنَّا نَتَحَيَّنُ، فَإِذَا زَالَتِ الشَّمْسُ رَمَيْنَا‏.‏
Reference : Sahih al-Bukhari 1746
In-book reference : Book 25, Hadith 224
USC-MSA web (English) reference : Vol. 2, Book 26, Hadith 802
  (deprecated numbering scheme)