Ibn Majah

Commentary: (1) (غُرٌّ) is the plural of (اَغَرُّ), by which is meant an animal (such as a horse, etc.) whose forehead is white, and (مُحَجَّل) refers to an animal whose legs are white. (بُلُق) is the plural of اَبْلَق, meaning a horse that is partly black and partly white. Such a horse stands out among black horses and can be recognized from afar.

(2)
From this, the honor of the Ummah of Muhammad becomes evident, because the radiance of the limbs due to the effect of ablution (wudu) is a special distinction of this Ummah.

(3)
The radiance of the limbs has been described as the effect of ablution (wudu). Thus, a Muslim who does not perform prayer will be deprived of this distinctive honor and will not be able to be distinguished from non-Muslims. What greater misfortune could there be than for the Prophet (sallallahu alayhi wa sallam) to refuse to recognize a person who claims to be from his Ummah?