Musnad Ahmad 868
It was narrated that `Ali bin Abi Talib (رضي الله عنه) said:
I was a man who emitted a great deal of madhi and I started to do ghusl in the winter, until the skin of my back became cracked. I mentioned that to the Prophet (ﷺ), or it was mentioned to him, and he said: “Do not do that. If you see madhi, then wash your private part and do wudoo’ as for prayer, but if water gushes out, then do ghusl.`
حَدَّثَنَا عَبِيدَةُ بْنُ حُمَيْدٍ التَّيْمِيُّ أَبُو عَبْدِ الرَّحْمَنِ، حَدَّثَنِي رُكَيْنٌ، عَنْ حُصَيْنِ بْنِ قَبِيصَةَ، عَنْ عَلِيِّ بْنِ أَبِي طَالِبٍ، رَضِيَ اللَّهُ عَنْهُ قَالَ كُنْتُ رَجُلًا مَذَّاءً فَجَعَلْتُ أَغْتَسِلُ فِي الشِّتَاءِ حَتَّى تَشَقَّقَ ظَهْرِي قَالَ فَذَكَرْتُ ذَلِكَ لِلنَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ أَوْ ذُكِرَ لَهُ قَالَ فَقَالَ لَا تَفْعَلْ إِذَا رَأَيْتَ الْمَذْيَ فَاغْسِلْ ذَكَرَكَ وَتَوَضَّأْ وُضُوءَكَ لِلصَّلَاةِ فَإِذَا فَضَخْتَ الْمَاءَ فَاغْتَسِلْ‏.‏