Hadith: When the Prophet (may Allah's peace and blessings be upon him) returned from the battle of the Trench and put down his arms and took a bath, Jibrīl (peace be upon him) came and said (to him): You had put down your arms? By Allah, we (i.e. the angels) have not put them down yet. So, set out for them

عن عائشة رضي الله عنها قالت: لمَّا رجعَ النبيُّ صلى الله عليه وسلم من الخَنْدَق، ووَضَعَ السِّلاحَ واغتسل، أتاه جِبْريلُ -عليه السلام-، فقال: «قد وضعتَ السِّلاحَ؟ واللهِ ما وضَعْناه، فاخرُج إليهم قال: فإلى أيْنَ؟ قال: ها هُنا، وأشار إلى بَنِي قُرَيْظَةَ، فخرج النبيُّ صلى الله عليه وسلم إليهم».
[صحيح] - [متفق عليه]

‘Ā'ishah (may Allah be pleased with her) reported: When the Prophet (may Allah's peace and blessings be upon him) returned from the battle of the Trench and put down his arms and took a bath, Jibrīl (peace be upon him) came and said (to him): "You had put down your arms? By Allah, we (i.e. the angels) have not put them down yet. So, set out for them." The Prophet (may Allah's peace and blessings be upon him) said: "Where to go?" Jibrīl said: "Towards this side", pointing towards the Banu Qurayzhah. So, the Prophet (may Allah's peace and blessings be upon him) headed towards them.
[Authentic hadith] - [Narrated by Bukhari & Muslim]

Explanation

When the Prophet (may Allah's peace and blessings be upon him) returned from the battle of the Trench, also known as the battle of the Confederates, after Allah had granted him victory against the disbelievers of the Quraysh and those who supported them, he entered his house, put down the war gear, and took a bath to wash away the dust of the battle. Jibrīl (peace be upon him) came and told him: You had put down your weapon, but the angels have not yet put them down and are still carrying theirs. Then he ordered him to set out to fight the Banu Qurayzhah, a Jewish community that lived at the outskirts of Madīnah, who betrayed the covenant of the Messenger of Allah (may Allah's peace and blessings be upon him) and helped the disbelievers. The Prophet (may Allah's peace and blessings be upon him) set out with his Companions, fought them, and Allah rewarded them with victory over their enemies.