מסכת כלים

פרק יח משנה ז

A bed's leg

that was tamei midras (from having borne the weight of a zav, zavah, niddah or yoledes),

and [after that] was attached to a bed

the entire [bed] is tamei midras;

if it was removed

it is tamei midras,

and the bed is tamei from contact with midras;

if it was tamei with seven-day tumah (this is the tumah an object incurs from a cadaver)

if it was removed

it is tamei with seven-day tumah

and the bed is tamei the tumah of a night (i.e. it may be immersed immediately and becomes tahor that night);

if it was tamei the tumah of a night

the entire bed is tamei the tumah of a night,

if it was removed

it is tamei the tumah of a night

and the bed is tahor (as the leg, which was only a rishon, cannot impart its tumah to another object by contact);

and similarly the tooth of a mattock (an tool with a head one side of which has an axe-like blade, and the other side is shaped like an adze; others interpret this as another agricultural implement like pitchfork or soil-tiller; if the metal head of the implement, or its "tooth," was tamei and was then attached to a new handle to form a complete utensil, the same rules would apply.)

A tefilah (this refers to the tefillin shel rosh, which has four compartments),

has four utensils (they each have their own status as a utensil, even when separated form each other),

(if after they had contracted tumah from a corpse) one removed the first compartment

and then fixed it (by replacing it with a new, tahor compartment),

it is tamei with the tumah of a corpse,

and so the second and so the third (if they were removed and replaced),

[if next] one removed the fourth,

but is tamei with the tumah of something that touched something tamei with the tumah of a corpse,

if he returned to the first

and removed and fixed it (replacing it again)

it is tamei due to contact [wth something tamei with the tumah of a corpse],

and so too the second [compartment],

remove the third (which had been the last remaining one that had been tamei due to contact with the original set)

it is tahor

as the fourth was [tamei] from contact [with something tamei with the tumah of a corpse]

and [something tamei from] contact cannot make [something else tamei] by contact.