When one purchases tefillin from a non-expert, how does one verify their validity through sampling?
Synopsis
The Mechaber establishes a sampling system: check 3 of 100 (two head and one hand, or vice versa). If valid, the entire batch is presumed valid — unless purchased in multiple bundles, in which case each bundle is sampled separately. A seller who testifies they belonged to a Torah scholar is believed without checking.
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Discussion
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