They are also agreed that if the period of intended residence is one during which, according to at least one of the opinions, the designation “traveller” is not lifted, and some impediment thereafter prevents him from resuming the journey, he may continue to shorten his prayers indefinitely, however long he is detained.

Whoever treats the shorter period of his stay as decisive will interpret the longer period cited by his opponents in a way that supports his own view. Thus the Mālikīs, for example, claim that the fifteen days the Prophet—peace and blessings be upon him—spent in Mecca in the Year of the Conquest were days during which he continually intended not to remain four full days; yet that very line of argument rebounds upon them with respect to the limit they themselves have set.

The sounder course for a jurist exercising ijtihād here is to adopt one of two approaches:

1. He may set the ruling according to the greatest length of time for which it is authentically reported that the Prophet—peace and blessings be upon him—stayed while shortening, and take that as the limit, on the grounds that the default is to perform the prayer in full and that no extension beyond this period is permissible without further evidence; or
2. He may hold that the default is the shortest period upon which consensus exists. Reports that the Prophet—peace and blessings be upon him—shortened for longer than that can then be understood in one of two ways: either he did so simply because it is permissible for a traveller, or he did so while intending only the period that is unanimously agreed upon, after which circumstances obliged him to stay longer. Since both possibilities remain, one must adhere to the original principle.

The shortest duration ever proposed is one day and one night, a view ascribed to Rabīʿah ibn Abī ʿAbd al-Raḥmān.

Al-Ḥasan al-Baṣrī is reported to have held that a traveller may shorten without limit until he reaches one of the settled towns, proceeding on the premise that the label “traveller” remains upon him until he enters such a city.

These, then, are the principal issues connected with shortening the prayer.

[Section Two: Combining the Prayers]

Section Two: On Combining (jamʿ)
Combining is related to three questions:

1. Its permissibility,
2. The manner in which it is performed, and
3. The circumstances that allow it.

Regarding permissibility, they are unanimously agreed that combining Zuhr and ʿAsr at the time of Zuhr in ʿArafāt is Sunnah, and that combining Maghrib and ʿIshāʾ at Muzdalifah at the time of ʿIshāʾ is likewise Sunnah.

They differ over combining elsewhere. The majority allow it—though they disagree about the particular situations in which it is or is not permissible—whereas Abū Ḥanīfah and his companions forbid it outright.

The reasons for their disagreement are three:
First, they differ in how they interpret the narrations concerning combining and what proof these provide, for all of them report actions rather than statements, and actions are far more open to multiple possibilities than explicit wording.
Second, they differ over the authenticity of some of those reports.
Third, they disagree on whether analogy may be employed in this matter. As you can see, these are three distinct causes.