The importance of reciting what the mueththin says in Azan.

 The importance of reciting what the mueththin says in Azan.

As reported it is sunnah to say whatever the mueththin says.

Except when he says haay ya alas solaah one should say wa laa hawla walaa quwwata illa billah.

And same as haay ya alal falaah one should say walaa hawla walaa quwwata illa Allah.

It was narrated that 'Alqamah bin Waqqas said:

I was with Mu'awiyah when the Mu'adhdhin called the Adhan. Muawiyah said what the Mu'adhdhin said, but when he said: 'Hayya 'alas-salah (come to prayer),' he said: 'La hawla wa la quwwata illa Billah (There is no power and nostrength except with Allah);' and when he said: 'Hayya 'alal-falah (come to prosperity),' he said: 'La hawla wa la quwwata illa Billah (There is no power and no strength except with Allah).' After that he said what the Mu'adhdhin said, then he said: 'I heard the Messenger of Allah (ﷺ) saying exactly like that

Sunan an Nasa'i

Vol. 1, Book 7, Hadith 678.

After the Azan, one should then send salawat to the Prophet peace be upon him and say,

Narrated Jabir bin `Abdullah:

Allah's Messenger (ﷺ) said, "Whoever after listening to the Adhan says, 'Allahumma Rabba hadhihi-dda` watit-tammah, was-salatilqa'imah, ati Muhammadan al-wasilata wal-fadilah, wa b`ath-hu maqaman mahmudan-il-ladhi wa`adtahu' [O Allah! Lord of this perfect call (perfect by not ascribing partners to You) and of the regular prayer which is going to be established, give Muhammad the right of intercession and illustriousness, and resurrect him to the best and the highest place in Paradise that You promised him (of)], then my intercession for him will be allowed on the Day of Resurrection".

Sahih al-Bukhari 614.