(2) باب قَصْرِ الصَّلاَةِ بِمِنًى
Ibn 'Umar reported:
The Messenger of Allah (ﷺ) said two rak'ahs at Mina, and Abu Bakr after him, and 'Umar after Abu Bakr, and 'Uthman at the beginning of his caliphate; then 'Uthman observed four rak'ahs, and when Ibn 'Umar prayed with the Imam, he said four rak'ahs, but when he observed prayer alone, he said two rak'ahs.
Reference: Sahih Muslim 694 c
In-book reference: Book 6, Hadith 23
USC-MSA web (English) reference(deprecated numbering scheme): Book 4, Hadith 1479