Language:
كتاب الأدب
78  
Good Manners and Form (Al-Adab)
(90)
Chapter: What kinds of poetry, Rajaz and Huda is allowed
(90)
باب مَا يَجُوزُ مِنَ الشِّعْرِ وَالرَّجَزِ وَالْحُدَاءِ وَمَا يُكْرَهُ مِنْهُ
Sahih al-Bukhari 6146

Narrated Jundub:

While the Prophet (ﷺ) was walking, a stone hit his foot and stumbled and his toe was injured. He then (quoting a poetic verse) said, "You are not more than a toe which has been bathed in blood in Allah's Cause."

حَدَّثَنَا أَبُو نُعَيْمٍ، حَدَّثَنَا سُفْيَانُ، عَنِ الأَسْوَدِ بْنِ قَيْسٍ، سَمِعْتُ جُنْدَبًا، يَقُولُ بَيْنَمَا النَّبِيُّ صلى الله عليه وسلم يَمْشِي إِذْ أَصَابَهُ حَجَرٌ فَعَثَرَ فَدَمِيَتْ إِصْبَعُهُ فَقَالَ ‏ "‏ هَلْ أَنْتِ إِلاَّ إِصْبَعٌ دَمِيتِ وَفِي سَبِيلِ اللَّهِ مَا لَقِيتِ ‏"‏‏.‏
Reference : Sahih al-Bukhari 6146
In-book reference : Book 78, Hadith 172
USC-MSA web (English) reference : Vol. 8, Book 73, Hadith 167
  (deprecated numbering scheme)