their prayer. However, this condition has been superseded by the Sunnah of the Messenger of Allah, peace and blessings be upon him, which he conveyed from his Lord. Umar ibn al-Khattab, may Allah be pleased with him, found this qualification problematic, so he asked the Prophet, peace and blessings be upon him, about it. The Prophet, peace and blessings be upon him, replied: “It is a charity which Allah has bestowed upon you, so accept His charity.” (1) Thus, permission to shorten the prayer in conditions of safety is a charity that Allah has bestowed upon us.
Some scholars have said that shortening the prayer falls into two categories: shortening its number of units and shortening its manner of performance. When fear and travel coincide, both forms of shortening apply. When only one of them is present, the form of shortening appropriate to it alone applies: when travel alone is present, the shortening is in the number of units; when fear alone is present, the shortening is in the manner of performance; and when both are present, both apply. This is a sound correspondence and an attempt to identify the effective cause and wisdom. However, what decisively settles the matter is the statement of the Messenger of Allah, peace and blessings be upon him: “It is a charity which Allah has bestowed upon you, so accept His charity.”
His statement, “He legislated for him the shortening of a four-unit prayer”: the four-unit prayers are three—Zuhr, Asr, and Isha. As for the three-unit prayer, it is not shortened, because if it were shortened, its intended odd-numbered character would be lost; and because it cannot be shortened by half, since there is no prayer consisting of one and a half units. Nor is the two-unit prayer shortened, because if it were shortened, it would become odd-numbered, and its intended character would thus be lost. This reasoning I have mentioned is only an explanation of the underlying wisdom; otherwise, the basic principle is to follow the textual evidence, for the number of units in the prayer is among those matters beyond the reach of human reason. We mention this only by way of explaining the correspondence: why was shortening prescribed only for the four-unit prayers?