Language:
كتاب العلم
3  
Knowledge
(51)
Chapter: Whosoever felt shy (to ask something) and then requested another person to ask on his behalf
(51)
باب مَنِ اسْتَحْيَا فَأَمَرَ غَيْرَهُ بِالسُّؤَالِ
Sahih al-Bukhari 132

Narrated `Ali:

I used to get the emotional urethral discharge frequently so I requested Al-Miqdad to ask the Prophet (ﷺ) about it. Al-Miqdad asked him and he replied, "One has to perform ablution (after it)." (See Hadith No. 269).

حَدَّثَنَا مُسَدَّدٌ، قَالَ حَدَّثَنَا عَبْدُ اللَّهِ بْنُ دَاوُدَ، عَنِ الأَعْمَشِ، عَنْ مُنْذِرٍ الثَّوْرِيِّ، عَنْ مُحَمَّدٍ ابْنِ الْحَنَفِيَّةِ، عَنْ عَلِيٍّ، قَالَ كُنْتُ رَجُلاً مَذَّاءً فَأَمَرْتُ الْمِقْدَادَ أَنْ يَسْأَلَ النَّبِيَّ صلى الله عليه وسلم فَسَأَلَهُ فَقَالَ ‏ "‏ فِيهِ الْوُضُوءُ ‏"‏‏.‏
Reference : Sahih al-Bukhari 132
In-book reference : Book 3, Hadith 74
USC-MSA web (English) reference : Vol. 1, Book 3, Hadith 134
  (deprecated numbering scheme)