Sahih Muslim , Book 20, Hadith 4612 (USC-MSA) ⓘ
It has been narrated on the authority of Ibn Umar that the Messenger of Allah said: There will be great benefit in the forelock of the horses until the Day of judgment.
حَدَّثَنَا يَحْيَى بْنُ يَحْيَى، قَالَ قَرَأْتُ عَلَى مَالِكٍ عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " الْخَيْلُ فِي نَوَاصِيهَا الْخَيْرُ إِلَى يَوْمِ الْقِيَامَةِ " .
also referenced under: Book 33, Hadith 141 (In-Book) & Hadith 1871 (Reference)