The polytheists kept us occupied on the day of the Trench from praying Dhuhr until the sun had set. This was before the verses concerning fighting had been revealed. Then Allah revealed, "And Allah sufficed the believers in fighting" [Ahzab 33:25].The Messenger of Allah ﷺ then ordered Bilal, who called the iqamah for the Dhuhr prayer, and he prayed it just as he used to pray it at its proper time. Then Bilal called the iqamah for Asr, and he prayed it as he used to pray it at its proper time. Then he gave the adhan for Maghrib, and he prayed it as he used to pray it at its proper time.
أخبرنا عمرو بن علي قال حدثنا يحيى قال حدثنا ابن أبي ذئب قال حدثنا سعيد بن أبي سعيد
شغلنا المشركون يوم الخندق عن صلاة الظهر حتى غربت الشمس وذلك قبل أن ينزل في القتال ما نزل فأنزل الله عز وجل {وكفى الله المؤمنين القتال} فأمر رسول الله ﷺ بلالا فأقام لصلاة الظهر فصلاها كما كان يصليها لوقتها ثم أقام للعصر فصلاها كما كان يصليها في وقتها ثم أذن للمغرب فصلاها كما كان يصليها في وقتها
Its isnad is sahih. Ahmad reported it, 3/25, from Yahya Qattan with the same wording, and it is also found in Kubra, hadith 1625. Ibn Khuzayma graded it sahih, hadith 996, as did Ibn Hibban (Mawarid), hadith 285. Abu Saeed is Khudri, and Saeed bin Abu Saeed is Maqburi.