Abu Ghalib said: I heard Sayyiduna Abu Umamah (may Allah be pleased with him) say: "The muezzins are the trustees of the Muslims, and the imams are guarantors." And he said: The adhan is dearer to me than the imamate.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2032