What one says on hearing the muezzin

It is narrated from Sayyiduna Abdullah bin Ukaym (may Allah be pleased with him) that when the Commander of the Believers, Sayyiduna Uthman bin Affan (may Allah be pleased with him), heard the sound of the adhan, he would say: "Marhaban bil-qa'ilina 'adlan, wa bis-salati marhaban wa ahlan (Welcome to those who raise the call of justice and truth (the mu'adhdhins), and to the prayer too a warm-hearted welcome and greeting)."
[Recorded by Ahmad bin Mani' in his Musnad, no. 240, and Ibn Abi Shaybah in his Musannaf: 3345.]

It is narrated from Sayyiduna Ali (may Allah be pleased with him) that when he heard the sound of the adhan he would say these words: "Ushhidu biha kulla shahid, wa atahammaluha 'an kulli jahid (I make every witness a witness to this (call of truth), and I take it upon myself (as a proof and responsibility) on behalf of every denier and rejecter)."
The chain of this narration contains Abd al-Rahman bin Ishaq al-Wasiti, a da'if (weak) narrator. Imam Ibn Abi Shaybah narrated this report in al-Musannaf (2291), and Imam al-Bayhaqi in al-Da'awat al-Kabir (41).

It is narrated from Sayyiduna Abu Umamah (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "When the caller (the mu'adhdhin) calls to the prayer, the gates of the heaven are opened and supplication is answered. So whoever is afflicted with some distress, grief or severe hardship should wait for the call of the mu'adhdhin; then when the mu'adhdhin says the takbir, he too should say the takbir; when he pronounces the testimony of faith, this person too should pronounce the testimony of faith; when the mu'adhdhin says 'hayya 'ala al-salah', this person too should say 'hayya 'ala al-salah'; and when he says 'hayya 'ala al-falah', this person too should say 'hayya 'ala al-falah'. Then he should recite this supplication: 'Allahumma rabba hadhihi al-da'wati al-tammah, da'wati al-haqqi al-mustajabah, al-mustajabi laha, da'wati al-haqqi wa kalimati al-taqwa, ahyina 'alayha, wa amitna 'alayha, wa-b'athna 'alayha, waj'alna min khiyari ahliha mahyana wa mamatana' (O Allah, Lord of this perfect call, of this true call which attains acceptance and whose call is heard, which is the call of truth and the word of piety: keep us alive upon it (faith and tawhid), grant us death upon it, raise us again upon it, and include us among its best people in both life and death). After that he should ask Allah Almighty for his need."
Imam al-Tabarani narrated this hadith in detail in the book al-Du'a through Abdullah bin Ahmad from al-Hakam bin Musa.
Also, Imam al-Hakim narrated it in detail in al-Mustadrak through al-Haytham bin Kharijah from al-Walid.
And Ahmad bin Mani' narrated it from al-Haytham, but his narration goes only as far as the words "and supplication is answered", and he did not mention the later part.

A man from Banu Hashim narrates from the Prophet (peace and blessings be upon him), like the previous hadith, that "when the Prophet (peace and blessings be upon him) heard the mu'adhdhin saying 'Allahu akbar, Allahu akbar' (Allah is the Greatest, Allah is the Greatest), he (peace and blessings be upon him) too would repeat the same words; when the mu'adhdhin said 'ashhadu an la ilaha illallah' (I bear witness that there is no god worthy of worship except Allah), he (peace and blessings be upon him) too would say the same; when he said 'ashhadu anna Muhammadan rasulullah' (I bear witness that Muhammad (peace and blessings be upon him) is the Messenger of Allah), he (peace and blessings be upon him) too would say what he said; but when the mu'adhdhin called 'hayya 'ala al-salah, hayya 'ala al-falah' (come to the prayer, come to success), he (peace and blessings be upon him) would say in reply: 'La hawla wa la quwwata illa billah' (there is no power to avoid sins and no strength to do good except with the help of Allah)."
There is weakness and a break (inqita') in its chain.

It is narrated from Sayyiduna Anas (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) halted for rest one night (in the last part of the night during a journey), then Sayyiduna Bilal (may Allah be pleased with him) gave the adhan, and he (peace and blessings be upon him) said: "Whoever says words like his (the mu'adhdhin's) words and bears witness as he bore witness, for him is Paradise."
Its chain is da'if (weak).