'Sayyiduna Anas (may Allah be pleased with him) reports that Sayyiduna Bilal (may Allah be pleased with him) was instructed to say the words of the adhan twice each, and the words of the iqamah once each. And Yahya added from Ibn 'Ulayyah that I asked Ayub about this, and he said that in the iqamah only the words "Qad qamatis salah" should be said twice.'