If a traveler catches one rak'ah behind a resident, does he complete his prayer or shorten it?

The questioner : May Allah preserve you, Shaykh. A traveling man entered the mosque during the 'Asr prayer and found that the imam had already prayed three rak'ahs. If the imam concludes the prayer, does the traveler stand up and complete the prayer as a four-rak'ah prayer, or does he shorten it?

The Shaykh : He must complete the prayer. If a traveler prays behind someone who completes the prayer, it is obligatory for him to complete it, whether he catches the prayer from the beginning or the end. The evidence for this is the generality of the saying of the Prophet (peace and blessings be upon him): . Ibn 'Abbas (may Allah be pleased with him) was asked: .