Non-traveller praying behind a imam who is a traveller
Question

                What is the ruling regarding the traveller leading the congregational prayer with the residents praying behind him?. So for instance, in Isha prayer the traveller will lead and give salaam after 2 rakahs, and the residents following with continue to prayer after salaam. Is this correct?.
Praise be to Allah.The Sunnah indicates that 
    it is permissible for a non-traveller to pray behind a traveller, so long as 
    the non-traveller offers his prayer in full and does not shorten it when the 
    traveller imam does so. This was narrated in a hadeeth which is attributed 
    to the Prophet  (peace and blessings of Allaah be upon him) and in which 
    there is some weakness, but it is in accordance with what is understood by 
    the four madhhabs and others. 
It was narrated that 
    ‘Imraan ibn Husayn (may Allaah be pleased with him) said: 
I went out on campaign with 
    the Messenger of Allaah  (peace and blessings of Allaah be upon him) and 
    I was present with him at the conquest [of Makkah]. He stayed in Makkah for 
    eighteen days, praying only two rak’ahs [in each four-rak'ah prayer], and he 
    said: ‘O people of the city, pray with four rak’ahs, for we are people who 
    are travelling.’” 
Narrated by Abu Dawood (no. 
    1229); classed as da’eef (weak) by al-Albaani in Da’eef Abi Dawood. 
Maalik narrated in 
    al-Muwatta’ (2/206) from Ibn Shihaab from Saalim  ibn ‘Abd-Allaah from 
    his father from ‘Umar ibn al-Khattaab that when he came to Makkah, he would 
    lead them in praying two rak’ahs, then he would say: “O people of Makkah, 
    complete your prayer for we are people who are travelling.” 
Ibn Qudaamah (may Allaah 
    have mercy on him) said:  
The scholars are 
    unanimously agreed that if the non-resident prays behind a traveller, and 
    the traveller says the salaam after two rak’ahs, the non-traveller must 
    offer the prayer in full. It was narrated that ‘Imraan ibn Husayn said:  I 
    was present with the Messenger of Allaah  (peace and blessings of Allaah 
    be upon him) at the conquest [of Makkah]. He stayed in Makkah for eighteen 
    days, praying only two rak’ahs [in each four-rak'ah prayer], and he said: ‘O 
    people of the city, pray with four rak’ahs, for we are people who are 
    travelling.’” Narrated by Abu Dawood. 
And because the prayer was 
    obligatory for him with four rak’ahs, so he does not have the right to omit 
    any of its rak’ahs, as would also have been the case if he had not been led 
    in prayer by a traveller. End quote. 
Al-Mughni 
    (2/64). 
Al-Kaasaani al-Hanafi (may 
    Allaah have mercy on him) said: 
A non-traveller following a 
    traveller (in prayer) is valid … then when the imam says the salaam after 
    praying two rak'ahs, the non-traveller should not say the salaam, because he 
    still has to complete his prayer, and if he were to say the salaam (at this 
    point) his prayer would be invalidated. Rather he should stand up and 
    complete the prayer with four rak’ahs, because the Prophet  (peace and 
    blessings of Allaah be upon him) said: “Complete it, O people of Makkah, for 
    we are people who are travelling.” 
When the imam who is 
    travelling says the salaam, he should say to the non-travellers who are 
    behind him: “Complete your prayer, for we are people who are travelling,” 
    following the example of the Prophet  (peace and blessings of Allaah be 
    upon him). End quote. 
Badaa’i’ al-Sanaa’i’ 
    (1/101). 
Shaykh Ibn Baaz (may Allaah 
    have mercy on him) said: 
If a non-traveller offers 
    an obligatory prayer such as Zuhr or ‘Asr or ‘Isha’ behind a traveller, then 
    he must pray four rak’ahs. Hence he must complete his prayer after the 
    traveller says the salaam following two rak’ahs. End quote. 
Majmoo’ Fataawa Ibn Baaz 
    (12/259). 
Shaykh Ibn ‘Uthaymeen (may 
    Allaah have mercy on him) said: 
It is permissible for the 
    traveller to be an imam for non-travellers, and when he says the salaam, the 
    non-travellers should stand up and complete the prayer after he has 
    finished. But the traveller who leads non-travellers in prayer should tell 
    them before he prays, “We are travelling so when we say the salaam, complete 
    the prayer,” because the Prophet  (peace and blessings of Allaah be upon 
    him) prayed in Makkah after the conquest and said: “Complete [your prayers] 
    O people of Makkah, for we are people who are travelling.” And he would lead 
    them in praying two rak'ahs, and they would complete their prayers after he 
    had finished. End quote. 
Majmoo’ Fataawa wa 
    Rasaa’il al-Shaykh Ibn ‘Uthaymeen (15/153) 
See also Nayl al-Awtaar 
    (3/199), al-Mawsoo’ah al-Fiqhiyyah (6/33). 
And Allaah knows best.