It was narrated that Abu Dharr said: "The Messenger of Allah (ﷺ) said: 'There is no Arabian horse but it is allowed to offer two supplications every Sahar (end of the night): O Allah, You have caused me to be owned by whoever You wanted among the sons of Adam, and you have made me belong to him. Make me the dearest of his family and wealth to him, or among the dearest of his family and wealth to him.'"
Source: sunnah.com
Other translations
Arabic
أَخْبَرَنَا عَمْرُو بْنُ عَلِيٍّ، قَالَ أَنْبَأَنَا يَحْيَى، قَالَ حَدَّثَنَا عَبْدُ الْحَمِيدِ بْنُ جَعْفَرٍ، قَالَ حَدَّثَنِي يَزِيدُ بْنُ أَبِي حَبِيبٍ، عَنْ سُوَيْدِ بْنِ قَيْسٍ، عَنْ مُعَاوِيَةَ بْنِ حُدَيْجٍ، عَنْ أَبِي ذَرٍّ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " مَا مِنْ فَرَسٍ عَرَبِيِّ إِلاَّ يُؤْذَنُ لَهُ عِنْدَ كُلِّ سَحَرٍ بِدَعْوَتَيْنِ اللَّهُمَّ خَوَّلْتَنِي مَنْ خَوَّلْتَنِي مِنْ بَنِي آدَمَ وَجَعَلْتَنِي لَهُ فَاجْعَلْنِي أَحَبَّ أَهْلِهِ وَمَالِهِ إِلَيْهِ أَوْ مِنْ أَحَبِّ مَالِهِ وَأَهْلِهِ إِلَيْهِ " .
sunnah.com