(2) باب الصَّلاَةِ بِمِنًى
Narrated `Abdullah bin `Umar:
I offered the prayer with the Prophet, Abu Bakr and `Umar at Mina and it was of two rak`at. `Uthman in the early days of his caliphate did the same, but later on he started praying the full prayer.
Reference: Sahih al-Bukhari 1082
In-book reference: Book 18, Hadith 3
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 2, Book 20, Hadith 188