Ḥajjāj b. Minhāl > Ḥammād b. Salamah > Thābit > Anas

The Prophet ﷺ used to change his position during the Fajr prayer and he used to listen. If he heard the Adhan, he would stop, and if he didn't hear the Adhan, he would continue. – Sound Chain

حَدَّثَنَا حَجَّاجُ بْنُ مِنْهَالٍ حَدَّثَنَا حَمَّادُ بْنُ سَلَمَةَ عَنْ ثَابِتٍ عَنْ أَنَسٍ

أَنَّ النَّبِيَّ ﷺ كَانَ يُغِيرُ عِنْدَ صَلَاةِ الْفَجْرِ وَكَانَ يَسْتَمِعُ فَإِنْ سَمِعَ أَذَانًا أَمْسَكَ وَإِنْ لَمْ يَسْمَعْ أَذَانًا أَغَارَ – إسناده صحيح