Prayer: The Interval Between Adhan, Iqamah, and the Prayer
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 919
There must not be an interval between adhan and iqamah, and if an interval occurs to the extent that the adhan that was said cannot be regarded as being the adhan of that iqamah, then the adhan is invalid. Also, if there is an interval between the adhan and iqamah and the prayer to the extent that the adhan and iqamah cannot be regarded as being those of that prayer, then the adhan and iqamah are invalid.