«أَنْ يَخْدَعَ بِإِدْخَالِي الْمِخْدَعَ»
That he meant to trick me by sending me into the inner room.
The narrator explicitly says he did not suspect the plan when he left. Mikhdaʿ is the inner room; yakhdaʿ means “to deceive.” Their echo creates pointed sound play. In hindsight, the improbable list of cleansing supplies was a pretext for removing the host from the room.