Whenever Messenger of Allah ﷺ attacked some people, he would never attack them till it was dawn. If he heard the Adhan (i.e. call for prayer) he would delay the fight, and if he did not hear the Adhan, he would attack them immediately after dawn. We reached Khaibar at night.
سَمِعْتُ أَنَسًا ؓ يَقُولُ كَانَ رَسُولُ اللَّهِ ﷺ إِذَا غَزَا قَوْمًا لَمْ يُغِرْ حَتَّى يُصْبِحَ فَإِنْ سَمِعَ أَذَانًا أَمْسَكَ وَإِنْ لَمْ يَسْمَعْ أَذَانًا أَغَارَ بَعْدَ مَا يُصْبِحُ فَنَزَلْنَا خَيْبَرَ لَيْلاً