Sunan an-Nasa'i 627
سنن النسائي#627SahihIt was narrated that Anas said:"The Messenger of Allah (S.A.W) commanded Bilal to say the phrases of the Adhan twice and the phrases of the Iqamah once
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Abu GhuddahSahih
Al-AlbaniSahih
Zubair Ali ZaiIsnaad Sahih Agreed Upon
In-book reference: 7:2