Abdullah bin Umar reported,

During the time of the Messenger of Allah ﷺ, the call to prayer was given with each phrase repeated twice, and the iqamah was given with each phrase said only once, except that he would say, "The prayer has begun, the prayer has begun." When we heard the iqamah, we would perform ablution and then head out to the prayer.

Azami 1871

Hasan

عن ابن عمر قال

إنما كان الأذان على عهد رسول الله ﷺ مرتين مرتين، والإقامة مرة مرة غير أنه يقول: قد قامت الصلاة، قد قامت الصلاة، فإذا سمعنا الإقامة توضأنا، ثم خرجنا إلى الصلاة.

الأعظمي 1871حسن
Contents
Reference
Commentary
Ayat
Collection
Jami al-Kamil
Book
Prayer
Chapter
Adhan
Section
Repeating the adhan and saying the iqamah once, and that whoever gives the adhan should also give the iqamah
Numbering
Jami al-Kamil 1871 (2nd edition)
Azami 1871