Bukhari

Hadith Commentary:
(1)
Some scholars hold the view that the shortening of prayer (qasr) is specific to wartime circumstances.
As evidence, they present the verse of the Noble Qur’an in which, during travel, the shortening of prayer is conditioned upon emergency situations.
Imam Bukhari rahimahullah has clarified that during travel, even in a state of security, qasr may be performed.
The mention of fear of the enemy in the noble verse is due to the predominance of such circumstances, because at that time, the entire Arabian Peninsula had, for the Muslims, taken the form of a land of war (dar al-harb).
(2)
Imam Ibn al-Qayyim rahimahullah states that there are two types of qasr:
➊ Qasr of the pillars (arakan), meaning a reduction in the form and pillars of the prayer.
➋ Qasr of the number (adad), meaning a reduction in the number of units (rak‘at) of the prayer, i.e., two instead of four.
When both fear and travel are present, then absolute qasr is performed, i.e., both qasr of the pillars and qasr of the number.
When neither fear nor travel is present, the prayer must be performed in full.
When there is fear but not travel, then the prayer is performed in full with qasr of the pillars, i.e., there will be no reduction in the number of units, as was the case during the Battle of the Trench (Ghazwat al-Khandaq).
When there is no fear but only travel, then reduction in quantity is permissible, but reduction in the pillars is not allowed; this is called the prayer of security (salat al-amn), but in terms of reduction in units, it is called the shortened prayer (salat al-qasr).
With respect to all its pillars, this prayer is complete, as ‘Umar radi Allahu anhu said:
The prayer of travel is two units, Jumu‘ah is also two units, and likewise the ‘Eid prayer is two units—this is a complete prayer, not a shortened one.
This is established from the tongue of the Messenger of Allah sallallahu alayhi wa sallam, and whoever fabricates will be at loss.
(Musnad Ahmad: 1/37)
Imam Ibn al-Qayyim rahimahullah has presented this discussion in a very excellent manner.
(Zad al-Ma‘ad: 1/466)

Hadith Commentary:
(1)
In the Noble Qur’an, the shortening of prayer (qasar) is conditioned upon a state of fear. Harithah bin Wahb radi Allahu anhu has clarified that the aforementioned condition in the Noble Qur’an is one of concurrence, not restriction, because the Messenger of Allah sallallahu alayhi wa sallam led us in shortened prayer (qasar) at Mina, even though we had no fear or danger from any enemy there. In fact, in terms of numbers, we were never greater than at that time, and there was no kind of fear or danger present. Despite this, the Messenger of Allah sallallahu alayhi wa sallam led us in two rak‘ahs during our stay at Mina.

In any case, pilgrims should observe the shortening of prayer (qasar) during their stay at Mina, whether they pray in congregation at Masjid Khaif or perform it in their respective tents.

(2)
Imam Abu Dawud rahimahullah has established from this hadith the permissibility of shortened prayer (qasar) for the residents of Makkah during the days of Hajj, because Harithah radi Allahu anhu was a resident of Makkah.
(Sunan Abi Dawud, Al-Manasik, Hadith: 1965)

1:
According to these people, the reason for shortening the prayer (qasr) in Mina is not the rites of Hajj (manasik al-hajj), but rather the journey (safar).
The distance between Makkah and Mina is not such that a person would shorten the prayer (perform qasr) due to it.
And those who consider it permissible for the people of Makkah to shorten the prayer in Mina, in their view, the reason for qasr is not the journey, but rather the rite (nusuk) of Hajj itself.

1965. Commentary: From this it is understood that performing shortened prayers (qasr) in Mina is a part of the rites of Hajj; therefore, just like other travelers, the residents of Makkah will also perform shortened prayers (qasr) in Mina. However, after the completion of the obligatory acts of Hajj, it will not be permissible for the residents of Makkah to perform shortened prayers (qasr) in Mina.

1446. Commentary: Since all pilgrims in Mina are travelers, therefore all pilgrims will perform shortened prayers (qasr) in Mina. According to Imam Ahmad rahimahullah, this shortening (qasr) is due to Hajj, not due to travel. According to the Hanafis, those people who reside within the distance for shortening (masafat-e-qasr) from Mina will perform the full prayer, but this is not established from any hadith, nor is there any mention in any hadith that such a distinction was made among those who performed Hajj with the Messenger of Allah sallallahu alayhi wa sallam; for example, it was not said that the people of Makkah should not shorten their prayers, etc. The correct view is that all pilgrims will perform shortened prayers (qasr) in Mina. (The discussion regarding shortening due to fear has already passed.)