Ruling on tasmee’ and tahmeed in prayer
Question

                Is tasmee’ (saying Sami’a Allaahu liman hamidah) and tahmeed (saying Rabbana laka’l-hamd) in prayer obligatory or Sunnah? And should the one who is praying behind an imam say Sami’a Allaahu liman hamidah?.
Praise be to Allah.The scholars 
    differed concerning the ruling on saying tasmee’ (Sami’a Allaahu liman 
    hamidah) and tahmeed (Rabbana laka’l-hamd) in prayer. There are 
    two views: 
1 –The view 
    of the majority – the Hanafis, Maalikis and al-Shaafa’is – is that it is one 
    of the Sunnahs of prayer and is not one of the obligatory parts of the 
    prayer. 
2 –That it 
    is one of the obligatory parts of the prayer. This is the view of the 
    Hanbalis. 
Ibn Qudaamah 
    said in al-Mughni (1/578): 
The well 
    known view narrated from Ahmad is that the takbeer (saying “Allaahu akbar”) 
    when going down and coming up, the tasbeeh during the stage of bowing and 
    prostrating, saying Sami’a Allaahu liman hamidah and Rabbana wa 
    laka’l-hamd in prayer, and saying Rabb ighfir li between the two 
    prostrations, and the first tashahhud are all obligatory. This is also the 
    view of Ishaaq and Dawood. 
And it was 
    narrated in another report from Ahmad that it is not obligatory. This is the 
    view of the majority of fuqaha’, because the Prophet  (peace and 
    blessings of Allaah be upon him) did not teach it to the one who did not 
    pray properly, and it is not permissible to delay the explanation from the 
    time when it is needed. Ibn Qudaamah quoted several points as evidence that 
    it is obligatory: 

    1-The Prophet  (peace and 
    blessings of Allaah be upon him) enjoined it, and his command means that 
    something is obligatory.

    2-He did it, and he said: “Pray 
    as you have seen me praying.”

    3-Abu Dawood (857) narrated from 
    ‘Ali ibn Yahya ibn Khallaad from his paternal uncle that the Prophet  
    (peace and blessings of Allaah be upon him) said: “No one’s prayer is 
    complete unless he does wudoo’ … then says ‘Sami’a Allaahu liman hamidah,’ 
    until he is standing up straight.” Classed as saheeh by al-Albaani in 
    Saheeh Abi Dawood.

    4-The points at which these 
    adhkaar are recited are pillars or essential parts of the prayer, therefore 
    the dhikr at these points is obligatory, as in the case of standing.
With regard 
    to the hadeeth about the one who did not pray properly, in the hadeeth that 
    we quoted, mention is made of the Prophet  (peace and blessings of 
    Allaah be upon him) teaching that. It is something extra that must be 
    accepted, but the Prophet  (peace and blessings of Allaah be upon him) 
    did not teach him all the obligatory parts of the prayer, based on the 
    evidence that he did not teach him the tashahhud or the salaam. This is to 
    be understood as meaning that he taught him that which he saw him doing 
    badly. End quote. 
Shaykh Ibn 
    ‘Uthaymeen (may Allaah have mercy on him) said in al-Sharh 
    al-Mumti’ (3/433): 
The evidence 
    for that is as follows: 
1 – The 
    Messenger  (peace and blessings of Allaah be upon him) always did that, 
    and he never failed to say Sami’a Allaahu liman hamidah under any 
    circumstances. 
2 – It is 
    the sign of moving from bowing to standing up again. 
3 – The 
    Prophet  (peace and blessings of Allaah be upon him) said: “When he [the 
    imam] says ‘Sami’a Allaahu liman hamidah, then say ‘Rabbana wa 
    laka’l-hamd.” 
Based on 
    this, there are three points of evidence for tahmeed and only two for 
    tasmee’. End quote. 
Some of the 
    Hanbalis quoted as evidence for it being obligatory the hadeeth of 
    ‘Abd-Allaah ibn Buraydah from his father who said: The Prophet  (peace 
    and blessings of Allaah be upon him) said to me: “O Buraydah, when you raise 
    your head from bowing, say Sami’a Allaahu liman hamidah, Allaahumma 
    Rabbana laka’l-hamd mil’ al-samaa’i wa mil’a al-ard wa mil’a ma shi’ta min 
    shay’in ba’d (Allaah hears the one who praises Him, O Allaah our Lord, 
    to You be praise filling the heaven, filling the earth and filling whatever 
    else You will). Narrated by al-Daaraqutni (1/339). 
But this is 
    a da’eef (weak) hadeeth, as was stated by the scholars. See Ibn ‘Abd 
    al-Haadi in Tahqeeq al-Ta’leeq (1/394); al-Iraaqi in Tarh 
    al-Tathreeb (2/331); and al-Shawkaani in Nayl al-Awtaar (2/278). 
    See also al-Mawsoo’ah al-Fiqhiyyah (27/82, 92-93) 
In the 
    answer to question no. 43574 we have stated that we favour the view that 
    tasmee’ and tahmeed are obligatory, and that the one who is praying alone 
    should recite both tasmee’ and tahmeed, according to scholarly consensus and 
    the imam should also recite both. This is the view of the Shaafa’is and the 
    Hanbalis. But the one who is praying behind an imam should recite only the 
    tahmeed, and it is not prescribed for him to say the tasmee’, as is the view 
    of the majority. The evidence for that is also quoted in the question 
    referred to. 
And Allaah 
    knows best.