Is it permissible to say the iqaamah for prayer sitting when he is able to stand?
Question

                If I give the iqaamah for prayer sitting or in another room other than the place where I am going to pray, is that allowed?.
Praise be to Allah.
      The Sunnah is for the adhaan and iqaamah for prayer is to 
      be given standing. This is what the people have done from the time of the 
      Prophet (blessings and peace of Allah be upon him) until the present day. 
      The one who gives the adhaan sitting or gives the iqaamah sitting with no 
      excuse has done a bad action and has gone against the Sunnah. 

    This is a matter on which the scholars are unanimously agreed 
    that there is no difference of opinion among them. 

    It says in al-Mawsoo‘ah al-Fiqhiyyah (6/11): 

    The fuqaha’ are unanimously agreed that it is mustahabb for 
    the one who is reciting the iqaamah for prayer to do so standing, and it is 
    makrooh to do so sitting without an excuse, but if there is an excuse, there 
    is nothing wrong with it. … It is also makrooh to give the iqaamah whilst 
    walking or riding when travelling or otherwise without an excuse. End 
    quote. 

    It also says in al-Mawsoo‘ah al-Fiqhiyyah (15/264): 

    Giving the adhaan or iqaamah whilst sitting: 

    The fuqaha’ are unanimously agreed that it is makrooh for the 
    muezzin to give the adhaan whilst sitting except with an excuse, or if he is 
    giving the adhaan for himself, as the Hanafis and Maalikis say, because the 
    Prophet (blessings and peace of Allah be upon him) instructed Bilaal to 
    stand when he said: “Get up and give the call to prayer.” The muezzins of 
    the Messenger of Allah (blessings and peace of Allah be upon him) used to 
    give the adhaan whilst standing. And because standing makes the voice carry 
    further, and giving the adhaan and iqaamah whilst sitting is contrary to the 
    practice that has been handed down. 

    Among the Hanbalis, Ibn Haamid said: If he gives the adhaan 
    whilst sitting, it is invalid. This was the view of Shaykh Taqiy al-Deen, 
    who said that the adhaan given by one who is sitting down is not acceptable. 
    And Abu’l-Baqa’ narrated that it should be repeated if he gave the adhaan 
    whilst sitting down. 

    In the case of one who has an excuse, there is nothing wrong 
    with him giving the adhaan whilst sitting. Al-Hasan ibn Muhammad al-‘Abdi 
    said: I saw Abu Zayd, the Companion of the Messenger of Allah (blessings and 
    peace of Allah be upon him), whose legs had been injured (in jihad) for the 
    sake of Allah, giving the adhaan whilst sitting. End quote. 

    The Sunnah is not to walk whilst giving the iqaamah, and to 
    give the iqaamah in the place where one is going to pray, so that there will 
    not be an interval between the iqaamah and starting the prayer, and because 
    the iqaamah is an announcement that the prayer is about to begin. So one 
    should start to pray immediately after reciting the iqaamah. 

    ‘Abd-Allah ibn al-Imam Ahmad said in his Masaa’il 
    (61/220): I said to my father: Can a man walk whilst saying the iqaamah? He 
    said: I like him to stay where he is. End quote. 

    Ishaaq ibn Raahaywayh said: As for the muezzin, once he 
    starts to say the iqaamah, if he is the imam, he should not walk during the 
    iqaamah until he finishes it. End quote. 

    Masaa’il al-Imam Ahmad wa Ishaaq, 
    2/836 

    And Allah knows best.