ENOfficial
Narrated `Abdullah bin Mughaffal: The prophet said, "There is a prayer between the two Adhans (Adhan and Iqama), there is a prayer between the two Adhans." And then while saying it the third time he added, "For the one who wants to (pray).
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا عَبْدُ اللَّهِ بْنُ يَزِيدَ، قَالَ حَدَّثَنَا كَهْمَسُ بْنُ الْحَسَنِ، عَنْ عَبْدِ اللَّهِ بْنِ بُرَيْدَةَ، عَنْ عَبْدِ اللَّهِ بْنِ مُغَفَّلٍ، قَالَ قَالَ النَّبِيُّ صلى الله عليه وسلم " بَيْنَ كُلِّ أَذَانَيْنِ صَلاَةٌ بَيْنَ كُلِّ أَذَانَيْنِ صَلاَةٌ ـ ثُمَّ قَالَ فِي الثَّالِثَةِ ـ لِمَنْ شَاءَ ".
sunnah.com