Reference: Fataawa Noor ‘alad-Darb – Question No.6310, Pages 142-143, Volume 12
Question: What is the ruling of supplicating [to Allaah] during the adhaan?
Response: Following the caller of the adhaan, and responding to his call [at each stage] is better than supplicating.
So when he says [اللهُ أَكْبَرُ], then you say [اللهُ أَكْبَرُ].
And when he says [أَشْهَدُ أَنْ لَا إِلَهَ إِلَّا اللهُ], then you say [أَشْهَدُ أَنْ لَا إِلَهَ إِلَّا اللهُ].
And when he says [أَشْهَدُ أَنَّ مُحَمَّداً رَسُوْلُ اللهِ], then you say [أَشْهَدُ أَنَّ مُحَمَّداً رَسُوْلُ اللهِ].
And when he says [حَيَّ عَلَى الصَّلاَةِ], then you say [لَا حَوْلَ وَ لَا قُوَّةَ إِلَّا بِاللهِ].
And when he says [حَيَّ عَلَى الفَلَاحِ], then you say [لَا حَوْلَ وَ لَا قُوَّةَ إِلَّا بِاللهِ].
And when he says [الصَّلَاةُ خَيْرٌ مِنْ النَّوْمِ], then you say [الصَّلَاةُ خَيْرٌ مِنْ النَّوْمِ].
And when he says [اللهُ أَكْبَرُ], then you say [اللهُ أَكْبَرُ].
And when he say [لَا إِلَهَ إِلَّا اللهُ], then you say [لَا إِلَهَ إِلَّا اللهُ].
And [saying] this [at each stage of the adhaan] is better than supplicating and reciting the Qur.aan; that is because this is a specific remembrance which is [easily] missed by the passing of it’s time. And when the caller to prayer finishes [calling] the adhaan, then you say [اللَّهُمَّ رَبَّ هَذِهِ الدَّعْوَةِ التَّامَةِ، وَ الصَّلَاةِ القَائِمَةِ، آتِ مُحَمَّداً الوَسِيْلَةَ وَ الفَضِيْلَةَ وَ ابْعَثْهُ المَقَامَ المَحْمُوْدَ الَّذِي وَعَدْتَهُ]. Then, supplicate to Allaah (Ta’aala) for whatever you wish; indeed, the supplication [made] between the adhaan and the iqaamah is not rejected.