Chapter: Melodiousness (Tatrib) in the Adhan
517 - Sa'id ibn Mansur narrated to us, he said: Marhum ibn Abd al-Aziz narrated to us, he said: My father narrated to me, from Abu al-Zubayr—the mu'adhdhin of Bayt al-Maqdis (Jerusalem)—who said: Umar ibn al-Khattab (may Allah be pleased with him) came to us and said: "When you call the adhan, do so with measured pauses (tarassul), and when you perform the iqamah, do so with haste (ihdhim)."
Chapter: Repeating the Shahadah (Tarji') in the Adhan
I asked Ishaq about the tarji' (repetition of the shahadah) in the adhan, and he said: "It is a sunnah." I said: "What if he repeats it in the adhan quietly, to the extent that he lets his own ears hear it?" He said: "I hope it is permissible; it is good."
And I heard Ishaq—another time—saying: "The sunnah has passed regarding the adhan in various forms, all of which are valid; one does not negate the other. The consensus of the people of knowledge is that the adhan is performed in pairs. If one calls the adhan and repeats the phrases until he finishes saying 'I bear witness that Muhammad is the Messenger of Allah'—as was the practice of Abu Mahdhura—then that is good."