Utbah heard the Messenger of Allah ﷺ say: Do not cut the forelocks, manes, or tails of horse, for their tails are their means of driving flies, their manes provide them with warmth, and blessing is tide to their forelocks.  

أَنَّهُ سَمِعَ رَسُولَ اللَّهِ ﷺ يَقُولُ لاَ تَقُصُّوا نَوَاصِيَ الْخَيْلِ وَلاَ مَعَارِفَهَا وَلاَ أَذْنَابَهَا فَإِنَّ أَذْنَابَهَا مَذَابُّهَا وَمَعَارِفَهَا دِفَاؤُهَا وَنَوَاصِيهَا مَعْقُودٌ فِيهَا الْخَيْرُ  

[Machine] The Messenger of Allah (peace and blessings be upon him) forbade the trimming of horse's tails, their feathers, and their forelocks. He said, "Their tails are their fly whisks, their feathers are their armor, and their forelocks are tied with blessings until the Day of Judgment."  

نَهَى رَسُولُ اللهِ ﷺ عَنْ نَتْفِ أَذْنَابِ الْخَيْلِ وَأَعْرَافِهَا وَنَوَاصِيهَا وَقَالَ أَذْنَابُهَا مَذَابُّهَا وَأَعْرَافُهَا إِدْفَاؤُهَا وَنَوَاصِيهَا مَعْقُودٌ بِهَا الْخَيْرُ إِلَى يَوْمِ الْقِيَامَةِ  

"لا تَقُصُّوا نَوَاصِىَ الخَيْلِ؛ فَإِنَّهُ مَعْقودٌ بِنَواصِيهَا الخَيْرُ، وَلا أَعْرافَهَا؛ فَإِنَّهَا أَدْفَاؤهُا، وَلا أذنَابَهَا، فَإِنَّهَا مَذَابُّهَا".