Anas (RAA) narrated that the Messenger of Allah (ﷺ) said:
"A supplication made between the Adhan and Iqamah is never rejected." Related by An-Nasa'i and others, Ibn Hibban and others graded it as Sahih. (ID)
English reference (ID): Book 16, Hadith 1594 (ID)
Arabic reference (ID): Book 16, Hadith 1551 (ID)