Hadith.876 - Muawiya ibn Wahb asked Imam Jafar ibn Muhammad Al-Sadiq (as) about the adhan (call to prayer).
The Imam said: "Raise your voice and speak loudly when giving the adhan. When performing the iqamah (second call to prayer), use a slightly lower voice.
Do not delay your adhan and iqamah except until the time for prayer has arrived, and recite the iqamah quickly (with fluidity)."