The Prophet of Allah ﷺ said, "Allah and His angels send blessings upon the front row, and the muezzin is forgiven to the extent of his voice. Everything that hears him, moist or dry, bears witness for him, and he receives a reward equal to that of everyone who prays with him."
أخبرنا محمد بن المثنى قال حدثنا معاذ بن هشام قال حدثني أبي عن قتادة عن أبي إسحق الكوفي
أن نبي الله ﷺ قال إن الله وملائكته يصلون على الصف المقدم والمؤذن يغفر له بمد صوته ويصدقه من سمعه من رطب ويابس وله مثل أجر من صلى معه
[Sahih] Ahmad narrated it in 4/284 through the hadith of Muaz, and it is in Kubra, hadith 1610. Qatada was mentioned before, and Abu Ishaq was mentioned before, hadith 96, and both used the term "an" (indicating a non-direct transmission). Munziri graded it hasan in Targheeb wa Tarheeb, 1/176, and the hadith has supporting narrations, among them the preceding hadith.