Tirmidhi

1:
Shikal refers to a horse whose three legs are white and one is of another color, or a horse that has one white leg and the remaining legs are of another color.

In this narration of Imam al-Nasa'i rahimahullah, there are two teachers: Ishaq ibn Ibrahim and Isma'il ibn Mas'ud. The wording mentioned is that of Isma'il ibn Mas'ud. The chain (siyaq) of Ishaq ibn Ibrahim is different from this.

(1) The Prophet (sallallahu alayhi wa sallam) disliked "shikal" in horses for two reasons: It is possible that the experience of that era indicated that such horses were not as useful in battle. In the Arabic language, "shikal" refers to tying three legs of a horse. Thus, there is no good omen found in the word "shikal"; for this reason, it is possible that he disliked it due to its apparent meaning. An example of this is that it is Sunnah to slaughter an animal at the birth of a child, but the Prophet (sallallahu alayhi wa sallam) disliked the term "aqiqah" for it because the word contains the meaning of "uquq" (disobedience).

(2) Several other definitions of "shikal" have also been given, the details of which are present in the commentaries of hadith. Even today, horses have considerable importance in wars, although the nature of combat has changed.

Hadith Commentary:
Vocabulary of the Hadith:
Shikal:
Its explanation is coming in the next narration.
In addition, according to Ibn Waleed,
if the hand and foot on one side are white, then that horse is called shikal; and according to Abu Ubayd and the majority of linguists,
a horse with three white legs and one unmarked, or sometimes the opposite—three unmarked and one white leg—
and there are other statements as well regarding its explanation.

Benefits and Issues:
The explanation of "shikal" is interpolated.
That is, it was not stated by the Noble Prophet (sallallahu alayhi wa sallam).
Rather, it is from the narrator.
For this reason, Imam Nawawi (rahimahullah) has transmitted various opinions regarding its explanation.
Some justifications for its disliked status have also been mentioned.
The true reality is known only to Allah, the Exalted.
(‘Awn al-Ma‘bud)

Benefits and Issues:
In the previous hadith, it is mentioned that if the right foreleg is not white but the remaining three are white, then that is good.
So, from this hadith, the horse intended is one in which no other single leg is white and the remaining three are white.
And Allah knows best.