أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " بَيْنَ كُلِّ أَذَانَيْنِ صَلاَةٌ ـ ثَلاَثًا ـ لِمَنْ شَاءَ ".
Abdullah ibn Mughaffal reported that the Messenger of Allah ﷺ said, “Between every two calls there is a prayer” – three times – “for whoever wishes.”
also in Sahih al-Bukhari 627