Sunan Ibn Majah 720
سنن ابن ماجه#720SahihIt was narrated that Abu Sa'eed Al-Khudri said:"The Messenger of Allah said: 'When you hear the call (to prayer), say what the Mu'adh-dhin says
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniSahih
Muhammad Fouad Abd al-BaqiSahih
Shuaib Al ArnautSahih
Zubair Ali ZaiSahih Muslim
In-book reference: 3:15