It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that the Prophet (peace and blessings be upon him) said: That muezzin—Allah will forgive him up to the extent his voice reaches, and every dry and wet thing that his voice reaches will bear witness in his favor.
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 6201
Hadith Gradingحکم دارالسلام:حديث صحيح، وهذا إسناد قوي .