A knife which was found on the fourteenth [of Nissan] may be used immediately for slaughter; [but if it was found] on the thirteenth [of Nissan], he must immerse it again. And a meat cleaver, whether [found] on the thirteenth or on the four-teenth, he must immerse again; [unless] the fourteenth fell on the Sabbath, [in which case] he may slaughter with it immedi-ately; [but if it was found] on the fifteenth [of Nissan], he may slaughter with it immediately. [If] it was found tied to a knife, then it is [considered] as the knife.