Sahih al-Bukhari, Hadith 624 ⓘ
Narrated `Abdullah bin Mughaffal Al-Muzani: Allah's Messenger said thrice, "There is a prayer between the two Adhans (Adhan and Iqama)," and added, "For the one who wants to pray."
حَدَّثَنَا إِسْحَاقُ الْوَاسِطِيُّ، قَالَ حَدَّثَنَا خَالِدٌ، عَنِ الْجُرَيْرِيِّ، عَنِ ابْنِ بُرَيْدَةَ، عَنْ عَبْدِ اللَّهِ بْنِ مُغَفَّلٍ الْمُزَنِيِّ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " بَيْنَ كُلِّ أَذَانَيْنِ صَلاَةٌ ـ ثَلاَثًا ـ لِمَنْ شَاءَ " .
also referenced under: Book 10, Hadith 21 (In-Book) & Volume 1, Book 11, Hadith 597 (USC-MSA)