مِشْكَاةُ الْمَصَابِيحِ
Mishkat al-Masabih 361
Purification
How to act when relieving oneself - Section 2
وَعَن الحكم بن سُفْيَان قَالَ: كَانَ النَّبِيُّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ إِذَا بَالَ تَوَضَّأَ وَنَضَحَ فَرْجَهُ. رَوَاهُ أَبُو دَاوُد وَالنَّسَائِيّ
Al-Hakam b. Sufyan said that when the Prophet (ﷺ) passed water he performed ablution and sprinkled his penis. Abu Dawud and Nasa’i transmitted it.
Mishkat al-Masabih, 361صَحِيح (الألباني)