Narrated Anas bin Malik (RA):

Allah's Messenger (ﷺ) said: "A supplication made between the Adhan and Iqamah is not rejected." [Reported by an-Nasa'i and Ibn Khuzaimah graded it Sahih (authentic)].

وَعَنْ أَنَسٍ ‏- رضى الله عنه ‏- قَالَ : قَالَ رَسُولُ اَللَّهِ ‏- صلى الله عليه وسلم ‏-{ لَا يُرَدُّ اَلدُّعَاءُ بَيْنَ اَلْأَذَانِ وَالْإِقَامَةِ } رَوَاهُ النَّسَائِيُّ , وَصَحَّحَهُ اِبْنُ خُزَيْمَةَ .‏ [1]‏ .‏