His statement, “solid-black,” means pure black, with no other colour mixed into its blackness. This is akin to what occurs in the hadith of Aisha, may Allah be pleased with her: “You will be gathered on the Day of Resurrection barefoot, naked, and uncircumcised” (1). In the hadith of Abdullah ibn Unays, it adds: “destitute” (2)—meaning, with nothing in your possession. Thus, solid-black means that no other colour is mixed into its blackness. Some scholars, however, said that if it has two white spots above its eyes, it does not cease to be considered solid-black (3).

His statement, “only,” means: and nothing else. Grammarians say regarding its parsing that the letter fāʾ is superfluous, added merely to improve the wording, while qaṭṭ is a noun meaning “enough” or “only.” It is indeclinable with a sukūn ending, having been made indeclinable because it resembles a particle in form, being composed of two letters.

Ibn Mālik mentioned among the causes of a noun’s indeclinability:

“Such as formal resemblance, as in the two pronouns in ‘you came to us.’”

Why did he restrict the matter in this way? He did so for two reasons:

First, to exclude the red dog, the white dog, and the like. The Prophet ﷺ was asked—as related in the hadith of Abu Dharr—what distinguishes the black dog from the red dog and the yellow dog. He replied: “The black dog is a devil” (4).