What should the One Who hears the Mu'aththin say?

Question :

Is it authentic to say, after hearing the Athan and supplicating Allah for the Prophet's intercession, to add: "... which You have promised, verily, You do not break promises." - or is it enough to say: "... and raise him to a praiseworthy position." Also, regarding the Iqamah, what should be said when the Mu'aththin says: "... the prayer is beginning."?

Answer:

It is preferred for the Muslim when he hears the Athan, to repeat what the Mu'aththin says, except when he says: "Come to prayer, come to prayer, come to success, come to success." - because the Prophet said:
"When you hear the Mu'aththin, repeat what he says.

And Muslim narrated in his Sahih, on the authority of 'Umar bin Al-Khattab, may Allah be pleased with him, that when the Prophet heard the Athan, he would repeat what the Mu'aththin said, and when he heard the Mu'aththin say: "Come to prayer, come to success", he would say:
"There is no power and no strength except in Allah."

then he would repeat what the Mu'aththin said in the remainder of the Athan. Then, he would say:
"Whoever said this from his heart, will enter Paradise.

And he said:
"When you hear the Mu'aththin, repeat what he says, then invoke prayers on me, for whoever invokes prayers on me once, Allah sends ten prayers on him because of it. Then ask Allah to make me an intercessor, for it is a station in Paradise which is not fitting for any but a servant from among the servants of Allah, and I hope that I will be he; so whoever asks for intercession for me, (my) intercession will be permitted for him.

And Al-Bukhari narrated in his Sahih, on the authority of Jabir bin 'Abdullah, may Allah be pleased with him, that he said: Allah's Messenger SAW said:
"Whoever said, when he heard the call (to prayer): "O Allah! Lord of this perfect supplication and the established prayer, grant Muhammad intercession and a virtuous place and raise him to a praiseworthy position as You have promised him." - will have my intercession made permissible for him on the Day of Resurrection."

Al-Bayhaqi added, with a good chain of narration, on the authority of Jabir bin 'Abdullah, may Allah be pleased with him, after his words: "... as You have promised him." - the word: "... verily, You do not break promises."

And it is preferred to respond to one who calls the Iqamah as one responds to the Mu'aththin, when he says: "The prayer is beginning, the prayer is beginning." - to say likewise, as it is preferred, when the Mu'aththin says in the Athan of Fajr "Prayer is better than sleep." - to say the same, based upon the general meaning of the aforementioned Hadiths and others.

As for what has been narrated from him that he said at the time of the Iqamah: "Allah has established it and made it everlasting." - it is a weak Hadith and may not be depended upon. And through Allah is success attained.