When the Prophet ﷺ reached Marr al-Zahran during the year of the Conquest, he informed us that we would soon meet the enemy and ordered us to break our fast, so we all broke our fast.
حدثنا أحمد بن محمد بن موسى أنبأنا عبد الله بن المبارك أنبأنا سعيد بن عبد العزيز عن عطية بن قيس عن قزعة
لما بلغ النبي ﷺ عام الفتح مر الظهران فآذننا بلقاء العدو فأمرنا بالفطر فأفطرنا أجمعون
Muslim also narrated it in the Book of Fasting, chapter "The Reward of One Who Breaks His Fast While Traveling When He Undertakes Work," hadith no. 1120, from the hadith of Qazaah, through the same chain.