Sahih al-Bukhari, Volume 1, Book 4, Hadith 179 (USC-MSA) ⓘ

Narrated Zaid bin Khalid: I asked `Uthman bin `Affan about a person who engaged in intercourse but did no discharge. `Uthman replied, "He should perform ablution like the one for an ordinary prayer but he must wash his penis." `Uthman added, "I heard it from Allah's Messenger." I asked `Ali Az-Zubair, Talha and Ubai bin Ka`b about it and they, too, gave the same reply. (This order was canceled later on and taking a bath became necessary for such cases).

حَدَّثَنَا سَعْدُ بْنُ حَفْصٍ، حَدَّثَنَا شَيْبَانُ، عَنْ يَحْيَى، عَنْ أَبِي سَلَمَةَ، أَنَّ عَطَاءَ بْنَ يَسَارٍ، أَخْبَرَهُ أَنْ زَيْدَ بْنَ خَالِدٍ أَخْبَرَهُ أَنَّهُ، سَأَلَ عُثْمَانَ بْنَ عَفَّانَ ـ رضى الله عنه ـ قُلْتُ أَرَأَيْتَ إِذَا جَامَعَ فَلَمْ يُمْنِ قَالَ عُثْمَانُ يَتَوَضَّأُ كَمَا يَتَوَضَّأُ لِلصَّلاَةِ، وَيَغْسِلُ ذَكَرَهُ‏.‏ قَالَ عُثْمَانُ سَمِعْتُهُ مِنْ رَسُولِ اللَّهِ صلى الله عليه وسلم‏.‏ فَسَأَلْتُ عَنْ ذَلِكَ عَلِيًّا، وَالزُّبَيْرَ، وَطَلْحَةَ، وَأُبَىَّ بْنَ كَعْبٍ ـ رضى الله عنهم ـ فَأَمَرُوهُ بِذَلِكَ‏.‏