Language:
كتاب المغازى
64  
Military Expeditions led by the Prophet (pbuh) (Al-Maghaazi)
(29)
Chapter: The Ghazwa of Al-Khandaq or Al-Ahzab Battle
(29)
باب غَزْوَةُ الْخَنْدَقِ وَهْىَ الأَحْزَابُ
Sahih al-Bukhari 4109

Narrated Sulaiman bin Surd:

On the day of Al-Ahzab (i.e. clans) the Prophet (ﷺ) said, (After this battle) we will go to attack them(i.e. the infidels) and they will not come to attack us."

حَدَّثَنَا أَبُو نُعَيْمٍ، حَدَّثَنَا سُفْيَانُ، عَنْ أَبِي إِسْحَاقَ، عَنْ سُلَيْمَانَ بْنِ صُرَدٍ، قَالَ قَالَ النَّبِيُّ صلى الله عليه وسلم يَوْمَ الأَحْزَابِ ‏ "‏ نَغْزُوهُمْ وَلاَ يَغْزُونَنَا ‏"‏‏.‏
Reference : Sahih al-Bukhari 4109
In-book reference : Book 64, Hadith 153
USC-MSA web (English) reference : Vol. 5, Book 59, Hadith 435
  (deprecated numbering scheme)