كتاب الجهاد والسير
32  
The Book of Jihad and Expeditions
(39)
Chapter: The persecution suffered by the prophet (saws) at the hands of the idolaters and hypocrites
(39)
باب مَا لَقِيَ النَّبِيُّ صلى الله عليه وسلم مِنْ أَذَى الْمُشْرِكِينَ وَالْمُنَافِقِينَ ‏‏
Sahih Muslim 1796 a

It has been narrated on the authority of Jundub b. Sufyan who said:

A finger of the Messenger of Allah (ﷺ) was wounded in one of the encounters He said: Thou art just a little finger which has bled, and what thou hast experienced is in the cause of Allah.
حَدَّثَنَا يَحْيَى بْنُ يَحْيَى، وَقُتَيْبَةُ بْنُ سَعِيدٍ، كِلاَهُمَا عَنْ أَبِي عَوَانَةَ، قَالَ يَحْيَى أَخْبَرَنَا أَبُو عَوَانَةَ، عَنِ الأَسْوَدِ بْنِ قَيْسٍ، عَنْ جُنْدُبِ بْنِ سُفْيَانَ، قَالَ دَمِيَتْ إِصْبَعُ رَسُولِ اللَّهِ صلى الله عليه وسلم فِي بَعْضِ تِلْكَ الْمَشَاهِدِ فَقَالَ ‏ "‏ هَلْ أَنْتِ إِلاَّ إِصْبَعٌ دَمِيتِ وَفِي سَبِيلِ اللَّهِ مَا لَقِيتِ ‏"‏ ‏.‏
Reference : Sahih Muslim 1796a
In-book reference : Book 32, Hadith 136
USC-MSA web (English) reference : Book 19, Hadith 4426
  (deprecated numbering scheme)