Verse 5 begins with athāfiyya, but its syntax depends on the preceding ʿaraftu al-dāra (“I recognized the dwelling”). The commentary understands the word through an appositional/badal relation: as if the speaker said, “I recognized the dwelling—its hearthstones and its channel.”
Sufʿan describes the darkened condition of the stones. Without this cross-verse link, verse 5 becomes an isolated list. With it, the hearth and channel are understood as the evidence supporting the recognition claimed in verse 4.