Shortening Salah in Mina (Ahadith 887 - 889)


Assalamu`alaykum,
Bismillah.

Volume 2, Book 20, Number 188:
Narrated 'Abdullah bin 'Umar:
I offered the prayer with the Prophet, Abu Bakr and 'Umar at Mina and it was of two Rakat. 'Uthman in the early days of his caliphate did the same, but later on he started praying the full prayer.

Volume 2, Book 20, Number 189:
Narrated Haritha bin Wahab:
The Prophet I led us in the prayer at Mina during the peace period by offering two Rakat.

Prophet (SAW) shortened prayer in Mina. In the description of hajj on IslamQA, it says:
..Then the pilgrim should go out to Mina and pray Zuhr, ‘Asr, Maghrib, ‘Isha’ and Fajr there, shortening the prayers but not joining them, because the Prophet (peace and blessings of Allaah be upon him) used to shorten his prayers in Mina but he did not join them. Shortening the prayers means making the four-rak’ah prayers two raka’ahs. The people of Makkah and others should shorten their prayers in Mina, ‘Arafah and Muzdalifah because the Prophet (peace and blessings of Allaah be upon him) used to lead the people in prayer during the Farewell Pilgrimage and there were people from Makkah with him, but he did not tell them to offer their prayers in full. If it had been obligatory for them to do so, he would have told them to do so as he did on the day of the Conquest of Makkah. But since the city has spread and incorporated Mina so that it is like one of the quarters of Makkah, then the people of Makkah should not shorten their prayers there. 
Volume 2, Book 20, Number 190:
Narrated 'Abdur Rahman bin Yazid:
We offered a four Rakat prayer at Mina behind Ibn 'Affan . 'Abdullah bin Masud was informed about it. He said sadly, "Truly to Allah we belong and truly to Him we shall return." And added, "I prayed two Rakat with Allah's Apostle at Mina and similarly with Abu Bakr and with 'Umar (during their caliphates)." He further said, "May I be lucky enough to have two of the four Rakat accepted (by Allah)."

Regarding the above Hadith, I shall update this post when I find some background information on it inshaAllah.
Wassalam.