Albert Barnes Commentary 1 Chronicles 26:16

"To Shuppim and Hosah westward, by the gate of Shallecheth, at the causeway that goeth up, watch against watch." — 1 Chronicles 26:16 (ASV)

All recent commentators seem to agree that the words “to Shuppim” should be removed, as the name appears to have arisen from an accidental repetition of the preceding word, “Asuppim.”

The gate Shallecheth—literally, “the gate of projection”—was the gate through which the sweepings of the temple, such as the ashes, the offal from the victims, and similar waste, were “thrown out.”

The causeway of the going up—compare the marginal reference note.

Ward against ward means “watch opposite to watch.” Hosah was in charge of both the western gate of the temple and the gate Shallecheth, which was in the outer wall opposite it. Therefore, he had to keep two watches, one opposite the other.