Can You Give Adhan Sitting Down?
Question

I was wondering is it permissible to do the adhan for a Masjid or a musalla whilst one is sitting down or lying down on one’s back? Could you please provide any daleel from the Quran and Sunnah.
Praise be to Allah.The Sunnah of Standing When Giving Adhan
The Sunnah is for the Mu’adhdhin to give the Adhan whilst standing, as the muezzin of the Messenger of Allah (blessings and peace of Allah be upon him) used to do and as the Muslims have done from then until the present day. There is consensus on this matter.
If he gives the Adhan whilst sitting or lying down without an excuse, his Adhan is valid but disliked.
Ibn Qudamah (may Allah have mercy on him) said: He should give the Adhan standing. Ibn Al-Mundhir said: All of the scholars from whom I have acquired knowledge agreed that the Sunnah is to give the Adhan standing. According to the Hadith of Abu Qatadah that we have quoted, the Prophet (blessings and peace of Allah be upon him) said to Bilal: “Stand up and give the call to prayer.” The muezzins of the Prophet (blessings and peace of Allah be upon him) used to give the call to prayer standing.
Exceptions to Standing during Adhan
If he has an excuse, then there is nothing wrong with him giving the call whilst sitting. Al-Hasan Al-`Abdi said: I saw Abu Zayd, the Companion of the Messenger of Allah (blessings and peace of Allah be upon him) when his legs had been injured (in battle) for the sake of Allah, giving the Adhan whilst seated. This was narrated by Al-Athram.
What Happens If Adhan Is Given While Sitting?
If he gives the Adhan whilst sitting without an excuse, then this is regarded as disliked by the scholars, although it is valid. This issue is not more important than that of giving a Khutbah, and it is valid if done by one who is sitting. (End quote from Al-Mughni, 1/253)
This version of the Hadith of Abu Qatadah was also narrated by Al-Bukhari (595)
Facing the Qiblah While Giving the Adhan
An-Nawawi (may Allah have mercy on him) said: The Sunnah is to give the call to prayer standing and facing towards the Qiblah. If he gives the call sitting or lying down, or not facing towards the Qiblah, it is disliked but his Adhan is valid, because the aim is to announce the prayer, and this has been achieved. (End quote from Al-Majmu`, 3/114)
For more details, please see the following answers:
How to Call Adhan
Who Should Give Adhan?
Is Adhan Necessary for Prayer?
How Was the Adhan Prescribed in Islam?
And Allah knows best.