مِشْكَاةُ الْمَصَابِيحِ
Mishkat al-Masabih 679
Prayer
The Excellence of the Adhan and the Response to the Mu’adhdhin - Section 3
وَعَنْهُ قَالَ: كُنَّا نُؤْمَرُ بِالدُّعَاءِ عِنْدَ أَذَانِ الْمغرب. رَوَاهُ الْبَيْهَقِيّ
He said, “We used to receive command to make a supplication when the call to the sunset prayer was being made.” Baihaqi transmitted it in ad-Da'awal al-kabir.
Mishkat al-Masabih, 679لم تتمّ دراسته (الألباني)