Hadith: When you hear the Muezzin, say what he says and then invoke Allah's blessings upon me

عن عبد الله بن عمرو بن العاص أنه سمع النبي صلى الله عليه وسلم يقول: «إذا سمعتم المؤذن فقولوا مثل ما يقول ثم صلوا علي، فإنه من صلى علي صلاة صلى الله عليه بها عشرًا، ثم سلوا الله لي الوسيلة، فإنها منزلة في الجنة، لا تنبغي إلا لعبد من عباد الله، وأرجو أن أكون أنا هو، فمن سأل لي الوسيلة حَلَّت له الشفاعة».
[صحيح] - [رواه مسلم]

‘Abdullāh ibn ‘Amr ibn al-‘Ās (may Allah be pleased with him) reported: I heard the Prophet (may Allah’s peace and blessings be upon him) say: "When you hear the Muezzin, say what he says and then invoke Allah's blessings upon me, for whoever invokes Allah's blessings upon me one time, Allah will bestow His blessings upon him ten times. Then ask Allah to grant me the Wasīlah, which is a high rank in Paradise that befits only one of Allah's servants; and I hope that will be me. If anyone asks the Wasīlah for me, it becomes incumbent upon me to intercede for him."
Sahih/Authentic. - [Muslim]

Explanation

‘Abdullāh ibn ‘Amr ibn al-‘Ās (may Allah be pleased with him) reported that he heard the Prophet (may Allah’s peace and blessings be upon him) clarify the Sunnah in responding to the Muezzin and that it is linked to hearing the Adhān. His statement "say what he says" applies to all words of the Adhān except "Hayya ‘ala as-salāh" and "Hayya ‘ala al-falāh", after which one should say: Lā hawla walā quwwata illa billāh. "And then invoke Allah's blessings upon me" indicates that one should say it after he has finished repeating after the Muezzin. Whoever invokes Allah's blessings upon me one time will receive ten times as much from Allah Almighty. Allah's blessings upon His servant mean that He praises him among the angels. Then, ask Allah Almighty to grant me the Wasīlah, which is the highest rank ever in Paradise that befits only one servant of Allah, and I hope I will be that one. The Prophet (may Allah’s peace and blessings be upon him) said this out of modesty, because if this rank can only be given to one person, this one must be him, for he is the best of all creation. Nonetheless, supplication should be made for this rank. Moreover, Allah Almighty may elevate his rank further by virtue of the plentiful supplication of his Ummah, as He did by their invocation of His blessings upon him. Besides, they will attain rewards for this and win the Prophet's intercession on the Day of Judgment.