The appointed successor may shorten the prayer alone because he did not follow a resident.

276 - Issue: He said: "And if a traveler and a resident pray behind a traveler, the resident completes [the prayer] when his Imam performs the taslim."

Scholars have reached a consensus that if a resident follows a traveler, and the traveler performs the taslim after two rak'ahs, the resident must complete the prayer. It has been narrated from Imran ibn Husayn who said: "I witnessed the conquest with the Messenger of Allah (peace and blessings of Allah be upon him), and he stayed in Mecca for eighteen nights, praying only two rak'ahs, then he would say to the people of the city: 'Perform four, for we are travelers.'" Narrated by Abu Dawud. This is because the prayer is obligatory upon him as four, so he is not permitted to omit any of its rak'ahs, just as if he had not followed a traveler.

Section: It is recommended for an Imam, if he leads residents in prayer, to say to them after his taslim: "Complete your prayer, for we are travelers." This is due to the aforementioned hadith, and so that the number of rak'ahs of the prayer does not become confused for the ignorant, lest he think that the four-rak'ah prayer is only two. Al-Athram narrated from al-Zuhri that Uthman only completed the prayer because the Bedouins had performed Hajj, and he wanted to teach them that the prayer consists of four [rak'ahs].

Section: When a traveler leads residents and completes the prayer with them, their prayer is complete and valid. This is the opinion of al-Shafi'i and Ishaq. Abu Hanifah and al-Thawri said: The prayer of the residents is corrupted, while the prayer of the Imam and the travelers with him is valid. A similar view is narrated from Ahmad. The Qadi said: This is because the latter two rak'ahs are considered supererogatory (nafl) for the Imam, and thus he cannot lead those performing the obligatory (fard) prayer with them. Our argument is that a traveler is bound to complete the prayer by his intention, so the entirety of it becomes obligatory, and even if it were supererogatory...