بُلُوغُ الْمَرَامِ
Bulugh al-Maram 201
The Book of Prayer
وَعَنْ أَبِي هُرَيْرَةَ - رضى الله عنه - قَالَ : قَالَ رَسُولُ اَللَّهِ - صلى الله عليه وسلم -{ اَلْمُؤَذِّنُ أَمْلَكُ بِالْأَذَانِ , وَالْإِمَامُ أَمْلَكُ بِالْإِقَامَةِ } رَوَاهُ اِبْنُ عَدِيٍّ وَضَعَّفَهُ . [1]
Narrated Abu Hurairah (RA): Allah's Messenger (ﷺ) said: "The Mu'adhdhin has more right to [determine the time to] announce the Adhan and the Imam has more right to [determine when to] pronounce the Iqamah." [Reported by Ibn 'Adi who graded it Da'if (weak)].
Sunnah.com reference: Book 2, Hadith 64