Musnad Ahmad 1153:354

Abu Abd al-Rahman narrated to us, Haywah ibn Shurayh narrated to us, he said: Nafi ibn Sulayman narrated to me, that Muhammad ibn Abi Salih narrated to him, from his father, that he heard Aisha, the wife of the Prophet, may God bless him and grant him peace, saying: The Messenger of God, may God bless him and grant him peace, said: "The Imam is a guarantor, and the Mu'adhdhin is a trustee. So may God guide the Imam, and may He forgive the Mu'adhdhin."