6. The Book of Prayer - Travellers - كتاب صلاة المسافرين وقصرها
56) Chapter:
Abdullah b. Mughaffal reported Allah's Messenger (ﷺ) u saying:
There Is between the two calls (Adhan and Iqama) a prayer. And he mentioned it three times, and at the third time he said: This applies to those who wish to do it.