He traced it back to the Prophet ﷺ, who said, "Camels are a source of pride for their owners, sheep are a blessing, and goodness is tied to the forelocks of horses until the Day of Resurrection."
حدثنا محمد بن عبد الله بن نمير حدثنا عبد الله بن إدريس عن حصين عن عامر
يرفعه قال الإبل عز لأهلها والغنم بركة والخير معقود في نواصي الخيل إلى يوم القيامة
Bukhari narrated it in the Book of Jihad and Expeditions, Chapter on Horses Whose Forelocks Have Good Tied to Them Until the Day of Resurrection, hadith 2850, 3119, and elsewhere, and Muslim narrated it in the Book of Leadership, Chapter on the Merit of Horses and That Good Is Tied to Their Forelocks, hadith 1873, from Muhammad bin Abdullah bin Numayr, through the same chain. Busiri said, This isnad is sahih according to the criteria of the two Shaykhs, for they both relied on all of its narrators.