Al-Husayn ibn Sa‘id from Ibn Abi Najran from Safwan ibn Mihran al-Jammal who said:
I heard Abu Abdillah عليه السلام say: “The Adhan is in pairs, two by two, and the Iqamah is in pairs, two by two.”
Ali Akbar al-Ghaffari
Tahdhīb al-Aḥkām fī Sharḥ al-Muqniʿah, vol. 2, p. 66