Ibn Majah

Benefits and Issues:

➊
The meaning of forgiveness of sins up to the extent that the voice reaches is that if there are so many sins that they fill such a vast space, even then they will be forgiven.

➋
The meaning of twenty-five good deeds being written for the one who performs the prayer in congregation may be that he will receive the reward of prayer multiplied by twenty-five, just as in other ahadith there is explicit mention of the reward being multiplied by twenty-five and twenty-seven times. See: (Sahih al-Bukhari, al-Adhan, Chapter: The Virtue of Congregational Prayer, Hadith: 646, 645)

646. Commentary: That is, even if, hypothetically, his sins were to fill the entire area where his voice reaches, still, due to the blessing of the adhan, he would be forgiven.

515. Commentary:
➊ The honor of the muezzin is such that he becomes deserving of forgiveness as vast and extensive as this. Or, this is a simile and illustration: that even if his sins were so numerous as to fill such a space, they would still be forgiven. And the louder he calls the adhan, the more he becomes deserving of forgiveness. Therefore, calling the adhan in a loud voice is recommended (mustahabb) and emphasized (mu’akkad).
➋ Minor sins (saghā’ir) are forgiven through the adhan and participation in the congregation. For the forgiveness of major sins (kabā’ir), repentance (tawbah) and the fulfillment of the rights of others (huqūq al-‘ibād) are necessary. However, Allah’s mercy is vast—if He wills, He may forgive.