If he recites “Is not Allaah the Best of judges?” in the prayer, should he say, “Bala (Yes indeed)?
Question

                Is saying “Bala (Yes indeed)” during the prayer after the verse “Is not Allaah the Best of judges?” [al-Teen 95:5] after other verses regarded as invalidating the prayer?.
Praise be to Allah.
    Firstly: 

    Speaking during prayer was permitted. The Prophet  (peace 
    and blessings of Allaah be upon him) and his companions used to return 
    salaams when they were praying. Then that was forbidden, and the scholars 
    are unanimously agreed that it is forbidden to speak during the prayer and 
    the prayer is invalidated if one does that knowingly and deliberately.  

    It was narrated that ‘Abd-Allaah ibn Mas’ood (may Allaah be 
    pleased with him) said: We used to greet the Messenger of Allaah  (peace 
    and blessings of Allaah be upon him) when he was praying, and he would 
    return the greeting. When we came back from being with the Negus, we greeted 
    him and he did not respond. We said: O Messenger of Allaah, we used to greet 
    you when you were praying and you would return the greeting. He said: “One 
    should concentrate fully in prayer.” Narrated by al-Bukhaari(1141) and 
    Muslim (538). 

    It was narrated that Zayd ibn Arqam said: We used to speak 
    during the prayer; a man would speak to his neighbour whilst they were 
    praying, until the verse was revealed: “And stand before Allaah with 
    obedience [and do not speak to others during the Salaah (prayers)]” 
    [al-Baqarah 2:238]. Then we were commanded to remain silent and 
    forbidden to speak. 

    Narrated by al-Bukhaari (1142) and Muslim (539). 

    Al-Nawawi said: 

    With regard to the words: “And stand before Allaah with 
    obedience [and do not speak to others during the Salaah (prayers)]” 
    [al-Baqarah 2:238], it was said: What is meant is obedient, or silent. 

    The phrase “Then we were commanded to remain silent and 
    forbidden to speak” indicates that all kinds of human speech are forbidden 
    during prayer. The scholars are unanimously agreed that speaking 
    deliberately during the prayer, knowing that it is forbidden and for no 
    purpose invalidates the prayer. End quote. 

    Sharh Muslim (5/27). 

    Secondly: 

    Al-Nawawi said in Adaab Qiraa’at al-Qur’aan: 

    Chapter on the etiquette that is dictated by need. 

    If he recites the words of Allaah (interpretation of the 
    meaning): “Allaah sends His Salaah (Graces, Honours, Blessings, Mercy) on 
    the Prophet (Muhammad), and also His angels (ask Allaah to bless and forgive 
    him)” [al-Ahzaab 33:56], it is mustahabb for him to say: “Sall-Allaahu 
    ‘alayhi wa sallama tasleeman (May Allaah send blessing and  peace upon 
    him).” 

    If one recites the verse “Is not Allaah the Best of 
    judges?” [al-Teen 95:5] or “Is not He (Allaah Who does that) Able to 
    give life to the dead?” [al-Qiyaamah 75:40], it is mustahabb to say: “Bala 
    wa ana ‘ala dhaalika min al-shaahideen (Yes indeed, and I am among those 
    who bear witness to that)”. If he recites “In what message after this 
    will they then believe?” [al-A’raaf 7:185] it is mustahabb to say “Aamantu 
    Billaah (I believe in Allaah).” 

    All of that it is mustahabb for the reciter to say whether 
    during prayer or otherwise.  

    A number of ahaadeeth have been narrated concerning that, 
    some of which are saheeh and some are da’eef. 

    Abu Dawood (884) narrated that Moosa ibn Abi ‘Aa’ishah said: 
    A man was praying on the roof of his house, and when he recited: “Is not 
    He (Allaah Who does that) Able to give life to the dead?” [al-Qiyaamah 
    75:40] he said: “Subhaanaka fa bala (Glory to be You, yes 
    indeed).” They asked him about that and he said: “I heard it from the 
    Messenger of Allaah  (peace and blessings of Allaah be upon him).” 
    Classed as saheeh by al-Albaani in Saheeh Abi Dawood. 

    It was narrated from Ismaa’eel ibn Umayyah: I heard a Bedouin 
    say: I heard Abu Hurayrah say: The Messenger of Allaah  (peace and 
    blessings of Allaah be upon him) said: ‘Whoever among you recites 
    Wa’l-teeni wa’l-zaytoon (“By the fig, and the olive” Soorat al-Teen 95), 
    when he reaches the end of it, “Is not Allaah the Best of judges?” 
    [al-Teen 95:5], let him say: “Bala wa ana ‘ala dhaalika min 
    al-shaahideen (Yes indeed, and I am among those who bear witness to 
    that)”.  Whoever recites La uqsimu bi yawm il-qiyaamah (“I swear 
    by the Day of Resurrection” Soorat al-Qiyaamah 75), when he reaches the 
    words “Is not He (Allaah Who does that) Able to give life to the dead?” 
    [al-Qiyaamah 75:40], let him say: “Bala (Yes indeed). And whoever 
    recites Wa’l-mursalaat (“By the winds (or angels or the Messengers 
    of Allaah) sent forth one after another” Soorat al-Mursalaat 77), when 
    he reaches the words “Then in what statement after this (the Qur’aan) 
    will they believe?” [al-Mursalaat 77:50], let him say: Aamanna Billaah 
    (We believe in Allaah).’ 

    Narrated by Abu Dawood (887). It was classed as da’eef by 
    al-Albaani in Da’eef Abi Dawood. 

    Shaykh Ibn ‘Uthaymeen said in al-Sharh al-Mumti’ 
    (3/397-399): 

    If the reciter says “Is not He (Allaah Who does that) Able 
    to give life to the dead?” [al-Qiyaamah 75:40], then he may say: Bala 
    (Yes indeed), or Subhaanaka fa bala (Glory be to You, yes indeed), 
    because there is a hadeeth about that from the Prophet  (peace and 
    blessings of Allaah be upon him) and Imam Ahmad stated that. Imam Ahmad 
    said: If he recites “Is not He (Allaah Who does that) Able to give life 
    to the dead?” [al-Qiyaamah 75:40] during prayer or otherwise, he may 
    say, “Subhaanaka fa bala (Glory be to You, yes indeed)” both in 
    obligatory and naafil prayers. 

    If he recites “Is not Allaah the Best of judges?” [al-Teen 
    95:5], he should say, “Subhaanaka fa bala (Glory be to You, yes 
    indeed)”.  

    If he recites, “Is there any ilaah (god) with Allaah?” 
    [al-Naml 29:60], he may say, La ilaaha ill-Allaah (There is no 
    god but Allaah). End quote. 

    Thus it is clear that these phrases are not included in the 
    speech that is forbidden during prayer and which invalidates it; rather what 
    is forbidden during prayer is normal human speech as the Prophet  (peace 
    and blessings of Allaah be upon him) said: “This prayer is not the right 
    place for any of the people’s speech.” Narrated by Muslim (537). 

    Al-Nawawi said: What this means is that it is not the right 
    place for any of the people’s usual speech and conversation. End quote. 

    And Allaah knows best.