Overall meaning:
Whenever the Prophet ﷺ was travelling and needed to press on, it was his custom to combine the noon (zuhr) and afternoon (ʿasr) prayers—either by bringing ʿasr forward into the time of zuhr or by delaying zuhr into the time of ʿasr—and likewise to combine the sunset (maghrib) and night (ʿishāʾ) prayers, by either advancing or delaying. In every case he chose whichever option was more convenient for him and for the companions with him. Thus the state of journeying became a reason for joining the two prayers within the time of one of them, for that period was now deemed the time for both.

Differences among the scholars:
The jurists have differed about combining. Many of the Companions and Successors allowed it, whether by advance or by delay; this is the position of al-Shāfiʿī, Aḥmad, and al-Thawrī, who rely on the reports from Ibn ʿAbbās and Ibn ʿUmar, including the hadith of Muʿādh: “When the Prophet ﷺ set out before the sun had begun to decline, he would postpone the noon prayer and combine it with the afternoon prayer, performing the two together; and if he set out after the sun had declined, he would perform noon and afternoon together and then resume his journey. If he set out before sunset, he would delay the sunset prayer until he performed it with the night prayer; and if he set out after sunset, he would hasten the night prayer and perform it together with the sunset prayer.” Reported by Aḥmad, Abū Dāwūd, and al-Tirmidhī.

Some leading scholars declared this narration sound, while others critiqued it; Muslim records its substance without mention of advancing a prayer.

Abū Ḥanīfah, his two associates, al-Ḥasan, and al-Nakhaʿī held that combining is impermissible. They construed the relevant hadiths as referring to a “formal” or “apparent” combination: namely, that one delays zuhr until the very end of its time, prays it, and then prays ʿasr at the beginning of its time; the same applies to maghrib and ʿishāʾ. This construal is forced and at odds with the plain sense of “combining,” which is to place both prayers in the time of one of them. It is further contradicted by the authentic instances of advance combining. Al-Khaṭṭābī and Ibn ʿAbd al-Barr noted that combining is a concession, whereas performing the first prayer at the end of its span and the second at the start of its span leaves a window so narrow that even many specialists could scarcely manage it—so what of the general populace?

Ibn Ḥazm, and one narration from Mālik, held that delayed combining is permissible but advance combining is not. They replied to the hadiths in line with the criticisms voiced by some scholars.

The jurists also disagreed on the legal basis for combining. Al-Shāfiʿī, Aḥmad, and the majority maintained that travel itself justifies both advance and delayed combining; this is also one narration from Mālik. The predominant view reported from Mālik, however, confines combining to