The traveler joins a resident imam in the third rak'ah

Question:
The questioner says: If I am traveling for three days, and I join a resident imam in the 'Asr prayer, and he is in the third rak'ah, and I catch it, do I say the taslim with the imam or do I complete the prayer?

Answer:
If you pray behind one who completes the prayer, it is obligatory for you to complete it. The Messenger (peace and blessings be upon him) said: So do not differ with him. Also, the Companions used to complete the prayer behind a resident. When the Companions traveled and prayed behind a resident, they would complete the prayer. Ibn 'Abbas was asked about that, and he said: That is the sunnah (recommended practice), meaning the sunnah of the Messenger (peace and blessings be upon him), that the traveler, if he prays behind one who completes the prayer, it is obligatory for him to complete it. Yes.