Sahih al-Bukhari 4123

Arabic

حَدَّثَنَا الْحَجَّاجُ بْنُ مِنْهَالٍ، أَخْبَرَنَا شُعْبَةُ، قَالَ أَخْبَرَنِي عَدِيٌّ، أَنَّهُ سَمِعَ الْبَرَاءَ ـ رضى الله عنه ـ قَالَ قَالَ النَّبِيُّ صلى الله عليه وسلم لِحَسَّانَ ‏ "‏ اهْجُهُمْ ـ أَوْ هَاجِهِمْ ـ وَجِبْرِيلُ مَعَكَ ‏"‏‏.‏

English translation

Narrated Al-Bara:The Prophet (ﷺ) said to Hassan, "Abuse them (with your poems), and Gabriel is with you (i.e, supports you)." (Through another group of sub narrators) Al-Bara bin Azib said, "On the day of Quraiza's (besiege), Allah's Messenger (ﷺ) said to Hassan bin Thabit, 'Abuse them (with your poems), and Gabriel is with you (i.e. supports you)

Reference: Sahih al-Bukhari 4123, Book of Military Expeditions led by the Prophet (pbuh) (Al-Maghaazi). English translation by Dr. Muhammad Muhsin Khan.