It was narrated from Abu Hurairah, who heard it from the mouth of the Messenger of Allah (ﷺ):
"The Mu'adhdhin will be forgiven as far as his voice reaches, and every wet and dry thing will bear witness for him." (JA)
English reference (JA): Vol. 1, Book 7, Hadith 646 (JA)
Arabic reference (JA): Book 7, Hadith 652 (JA)