Mukhtasar Bukhari (Abridged) 577 — Should prayer be shortened

Narrated Abdullah bin Umar (may Allah be pleased with them): I offered two rak'ahs of prayer in Mina along with the Prophet (peace be upon him), Abu Bakr (may Allah be pleased with him), and Umar (may Allah be pleased with him), and also with the Commander of the Faithful, Uthman (may Allah be pleased with him), during the early period of his caliphate (I also prayed two rak'ahs). After that, he started offering the full prayer.