The Messenger of Allah ﷺ said, "Between every two calls to prayer there is a prayer." He said this three times, and on the third he added, "For whoever wishes."In another narration, he added on the fourth, "For whoever wishes."
أن رسول الله ﷺ قال: بين كل أذانين صلاة قالها ثلاثا: قال في الثالثة: لمن شاء. وفي رواية: قال في الرابعة لمن شاء.
Bukhari narrated it in the chapter on adhan (624), and Muslim in the chapter on the prayer of travelers (838), both through Abdullah bin Burayda, from Abdullah bin Mughaffal, and he related the hadith. The second narration is found in Muslim.His saying, "between every two adhans," means the adhan and the iqama. Khattabi said, By "the two adhans" he meant the adhan and the iqama, applying one of the two names to the other, just as they say "the two black things" meaning dates and water, when in fact only one of them is truly black, and just as they say "the practice of the two Umars," meaning Abu Bakr and Umar. It is also possible that the name genuinely applies to each of them in its own right, since adhan in the language means announcement. So the adhan is an announcement of the arrival of the prayer time, while the iqama is an announcement to begin performing the prayer. End of quote.The exception "except Maghrib" occurs in some narrations outside the Sahihayn, but it is a shadh addition that contradicts what the reliable memorizers narrated. Hafiz mentioned this in Fath al-Bari (2/108) and attributed it to Bazzar. It comes through the narration of Hayan bin Ubaydullah, from Abdullah bin Burayda, from his father, in similar wording. He said, The narration of Hayan, whose name is pronounced with a fatha on the ha and on the ya, is shadh, because although he was considered trustworthy by Bazzar and others, he contradicted the reliable memorizers among the companions of Abdullah bin Burayda in both the isnad and the wording of the hadith. He then said, Ibn Jawzi transmitted in Mawduat, from Fallas, that he accused the aforementioned Hayan of fabrication.