Hadith 1004
وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ يَحْيَى بْنِ سَعِيدٍ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم رُئِيَ وَهُوَ يَمْسَحُ وَجْهَ فَرَسِهِ بِرِدَائِهِ فَسُئِلَ عَنْ ذَلِكَ فَقَالَ " إِنِّي عُوتِبْتُ اللَّيْلَةَ فِي الْخَيْلِ " .
Yahya related to me from Malik from Yahya ibn Said that the Messenger of Allah, may Allah bless him and grant him peace, was seen wiping the face of his horse with his cloak. He was questioned about it and said, "I was reproached in the night about horses." i.e. not taking care of them
Sahih Lighairihi (Salim al-Hilali)
Muwatta Malik 1004 · Book 21, Hadith 46