At the time of Azan the tilawat (recitation) of Quran and zikrullah should be stopped and we should act on the sunnah of replying to the Azaan. If we act on the sunnah nur will be created in the qalb and then when we recite the quran and make zikrullah with this nur-e-qalb we will gain even more enlightenment. Inshallah
From the sayings of Sheikh Abraraul Haqq Saheb. May Allah increase his Ilm and Hilm and enable us to gain from it.
Narrated Malik bin Al-Huwairith:
On my departure from the Prophet he said to me and to a friend of mine, “You two, pronounce the Adhan and the Iqama for the prayer and let the elder of you lead the prayer.”
Abu Said Al-Khudri RadhiAllahu anhu also said that he heard Allah’s Apostle SallAllahu alaihi wasallam say, “Whenever you hear the Adhan, “say what the Mu’adhdhin is saying.”