Chapter on Vessels
His statement, “Chapter”: a chapter is that through which one enters into a subject. The scholars, may Allah the Exalted have mercy on them, use the divisions of a book, a chapter, and a section.
A book is a collection of chapters that fall under one general category, while a chapter is a particular type within that category. For example, “grain” includes barley, corn, and rice, yet barley is one thing and rice is another.
Thus, the Book of Purification includes every category that may be described as purification or that is connected to it. The chapters, however, are types within that category, such as the Chapter on Waters, the Chapter on Ablution, and the Chapter on Ritual Bathing, and the like.
As for sections, they consist of issues distinguished from others by certain features, whether conditions or details. At times, they divide a chapter into sections because its issues are extensive—not because some of them have a particular ruling, but simply due to the length of the discussion.
His statement, “Vessels”: this is the plural of vessel, meaning a container. The author mentions them here, even though they are also connected to the Chapter on Foods—since foods can only be eaten from vessels—because they are connected to the Chapter on Waters. Water is a fluid substance that cannot be stored except in a vessel. This is why they mention the Chapter on Vessels after the Chapter on Waters.
It is known that, when something has two relevant contexts, it is more appropriate to mention it in the first context and refer back to it in the second, because if it is deferred