4כֵּלִים הַמְפֻצָּלִין שֶׁמְּחֻבָּרִין זֶה לָזֶה בְּמַסְמְרִים. כְּגוֹן מִסְפֹּרֶת שֶׁל פְּרָקִים וְאִזְמֵל שֶׁל רְהִיטְנִי וְכַיּוֹצֵא בָּהֶן. בִּשְׁעַת מְלָאכָה חִבּוּר לְטֻמְאָה וּלְהַזָּיָה. שֶׁלֹּא בִּשְׁעַת מְלָאכָה אֵינוֹ חִבּוּר לֹא לָזֶה וְלֹא לָזֶה. כֵּיצַד הֵן חִבּוּר לְטֻמְאָה וּלְהַזָּיָה. שֶׁאִם נִטְמָא אֶחָד מֵהֶן בִּשְׁעַת מְלָאכָה נִטְמָא הַשֵּׁנִי. וְאִם הִזָּה עַל אֶחָד מֵהֶן בִּשְׁעַת מְלָאכָה עָלְתָה הַזָּיָה לִשְׁנֵיהֶן וּכְאִלּוּ הֵן גּוּף אֶחָד. וְכֵיצַד אֵינוֹ חִבּוּר לֹא לְטֻמְאָה וְלֹא לְהַזָּיָה. שֶׁאִם נִטְמָא אֶחָד מֵהֶן שֶׁלֹּא בִּשְׁעַת מְלָאכָה לֹא נִטְמָא חֲבֵרוֹ. וְאִם נִטְמְאוּ שְׁנֵיהֶן וְהִזָּה עַל אֶחָד מֵהֶן שֶׁלֹּא בִּשְׁעַת מְלָאכָה לֹא טִהֵר חֲבֵרוֹ אַף עַל פִּי שֶׁהֵן מְחֻבָּרִין. וְזֶהוּ דִּין תּוֹרָה. אֲבָל מִדִּבְרֵי סוֹפְרִים גָּזְרוּ שֶׁיִּהְיוּ חִבּוּר לְטֻמְאָה אֲפִלּוּ שֶׁלֹּא בִּשְׁעַת מְלָאכָה גְּזֵרָה מִשּׁוּם שְׁעַת מְלָאכָה. וּלְעוֹלָם אִם נָגְעָה בְּאֶחָד מֵהֶן טֻמְאָה נִטְמָא חֲבֵרוֹ. וְכֵן גָּזְרוּ עֲלֵיהֶן שֶׁלֹּא יִהְיוּ חִבּוּר לְהַזָּיָה אֲפִלּוּ בִּשְׁעַת מְלָאכָה גְּזֵרָה מִשּׁוּם שֶׁלֹּא בִּשְׁעַת מְלָאכָה. וּלְעוֹלָם אִם הִזָּה עַל אֶחָד מֵהֶן לֹא טִהֵר חֲבֵרוֹ עַד שֶׁיַּזֶּה גַּם עָלָיו. הִנֵּה לָמַדְתָּ שֶׁכָּל מָקוֹם שָׁאַתָּה שׁוֹמֵעַ חִבּוּר לְטֻמְאָה וְאֵינוֹ חִבּוּר לְהַזָּיָה אֵין זֶה אֶלָּא גְּזֵרָה מִדִּבְרֵיהֶם עַל הַדֶּרֶךְ שֶׁבֵּאַרְנוּ:
The following laws apply when there are keilim that have several parts which are connected to each other with nails, e.g., a scissors that comes apart, the blade of a plane, or the like. At the time of work, they are considered as joined, with regard to both impurity and sprinkling. When work is not being performed with them, neither is considered as joined to the other. What is meant by saying that they are considered as joined, with regard to both impurity and sprinkling? That if one of the parts contracts impurity at the time work is being performed, the second also contracts impurity. Conversely, if water was sprinkled on one while work was being performed with them, the sprinkling is also effective with regard to the other and it is as if they are a single entity. What is meant by saying that they are not considered as joined, with regard to both impurity and sprinkling? That if one contracts impurity while work is not being performed with it, the other does not contract impurity. And if both had contracted impurity and one sprinkled the water on one at a time when work was not being performed, the other does not become pure, even though they were joined together at that time. This is the Scriptural Law. According to Rabbinic Law, however, it was decreed that they should be considered as joined with regard to impurity even at a time when work was not being performed. This decree was instituted as a safeguard for the law applying when work was being performed. Whenever impurity touches one of them, the other also becomes impure. They also decreed that they should not be considered as joined with regard to sprinkling, even at a time when work was being performed. This decree was instituted as a safeguard for the law applying when work was not being performed. Whenever one sprinkles the water on one of them, the other does not regain purity until the water is also sprinkled on the other. From this, it can be inferred that whenever it is mentioned that two entities are considered as joined with regard to impurity, but not with regard to sprinkling, this is merely a Rabbinic decree, following the pattern explained above.