—then there would have been ample reason to transmit that fact, and it would have reached us.
Had it been obligatory, he ﷺ would have performed it; indeed, had it merely been permissible, he would have performed it. Therefore, if a person performs Friday Prayer while travelling, his prayer is invalid, and he must repeat it as a shortened Zuhr prayer, because the traveller is not among those required to perform Friday Prayer.
If someone were to ask: “Does the Prophet’s ﷺ omission of Friday Prayer not indicate that it is legislated?”
The answer is: Yes, it does. For had it been legislated, it would have been an act of worship—and an obligatory duty at that. It is inconceivable that the Prophet ﷺ would abandon an obligation. Thus, when the reason for an act exists but the Messenger ﷺ did not perform it, it is known that doing it is an innovation. He ﷺ said: “Whoever does a deed that is not in accordance with our affair, it is rejected.” (1)
This is a beneficial principle for the student of knowledge: everything for which the reason existed during the time of the Messenger ﷺ, yet which he did not do—treating it as an act of worship is an innovation. The reason for Friday Prayer while travelling existed in the Prophet’s ﷺ time, yet he did not perform it. Therefore, if someone performs it, we say to him: “You have done a deed that is not in accordance with the command of Allah and His Messenger,” and it is thus a rejected deed.
As for a traveller in a town where Friday Prayer is established—for example, someone passing through a town during a journey who enters it to rest at midday and intends to continue travelling after Zuhr—Friday Prayer is obligatory upon him, due to the general purport of Allah’s saying: “O you who believe, when the call is made for prayer on Friday, hasten to the remembrance of Allah and leave off trade.” [al-Jumu‘ah 62:9] This is general in meaning. We do not know of any Companions who came to the Messenger of Allah ﷺ and remained until Friday abandoning Friday Prayer; rather, the apparent indication of the sunnah is that they prayed with the Prophet ﷺ.
The Zahiriyyah held that Friday Prayer is obligatory upon the traveller.