The Messenger of Allah ﷺ said, "Allah forgives the caller to prayer to the extent of the reach of his voice, and every moist and dry thing that hears his voice bears witness for him."
قال رسول الله ﷺ: يغفر الله للمؤذن مد صوته، ويشهد له كل رطب ويابس سمع صوته.
Imam Ahmad narrated it (6201), he said, Abu Jawwab told us, Ammar bin Raziq told us, from Amash, from Mujahid, from Ibn Umar, and he related the hadith. Abu Jawwab is Ahwas bin Jawwab, as Bazzar stated explicitly, for he narrated it from Muhammad bin Abdullah Mukharrami, who said, Abu Jawwab Ahwas bin Jawwab told us, with the same wording, except that he said, "and everything moist and dry that hears it responds to him," instead of his saying, "and it bears witness for him..." Kashf Astar (355).Tabarani also narrated it in Al-Kabir (12/398) through another route from Amash, with the same wording as Ahmad's hadith. Its chain is hasan on account of Ahwas bin Jawwab, and although he is among the narrators found in Muslim, Abu Hatim said of him, "Truthful," and Ibn Hibban said, "He was precise but sometimes erred," while Ibn Main and others affirmed his reliability. This is why Haythami said in Majma al-Zawaid (1828), "Ahmad, Tabarani in Al-Kabir, and Bazzar narrated it, except that he said, 'and everything moist and dry that hears it responds to him,' and its narrators are the narrators of the sahih." End of quote.This same meaning has also been narrated from Abu Hurairah with additional details, reported by Abu Dawud (515), Nasai (645), and Ibn Majah (724), but it contains Musa bin Abu Uthman, who is unknown.It was also narrated from Bara by Nasai (2/13) and from Abu Umama by Tabarani in Al-Kabir (7942), though neither of these is sahih. As for the hadith of Bara, see the chapters on the rows of prayer, the chapter on the merit of the first row.