The Messenger of Allah ﷺ said, "The caller to prayer is entrusted, and the imam is responsible. Allah, guide the imams aright and forgive the callers to prayer."
حدثنا موسى بن داود حدثنا زهير عن أبي إسحاق عن أبي صالح
قال رسول الله ﷺ المؤذن مؤتمن والإمام ضامن اللهم أرشد الأئمة واغفر للمؤذنين
Its isnad is sahih. Abu Hanifa (56) narrated it with this exact wording, and Humaydi (999) narrated it with some words rearranged. It was also narrated by Abu Dawud (517) in the Book of Prayer, chapter on what is required of the muezzin, Tirmidhi (207), Abdul-Razzaq (1838), Tabarani in Al-Kabir (8/343), Ibn Khuzayma (1528), and Ibn Hibban (362) (in Al-Mawarid).