Mishnah Negaim 13:8: A pure person who extended his head and most of his body into an impure house becomes impure. An impure person who extends his head and most of his body into a pure house makes it [the house] impure. A pure cloak of which a three-by-three [finger-length] piece entered an impure house becomes impure. [If it was] an impure [cloak], if he extended even the volume of an olive [of it] into a pure house, it makes [the house] impure.

טָהוֹר שֶׁהִכְנִיס רֹאשׁוֹ וְרֻבּוֹ לְבַיִת טָמֵא, נִטְמָא. וְטָמֵא שֶׁהִכְנִיס רֹאשׁוֹ וְרֻבּוֹ לְבַיִת טָהוֹר, טִמְּאָהוּ. טַלִּית טְהוֹרָה שֶׁהִכְנִיס מִמֶּנָּה שָׁלשׁ עַל שָׁלשׁ לְבַיִת טָמֵא, נִטְמְאָה. וּטְמֵאָה שֶׁהִכְנִיס מִמֶּנָּה אֲפִלּוּ כַזַּיִת לְבַיִת טָהוֹר, טִמְּאַתּוּ:

Mishnah Negaim 13:9: One who enters a house with a Nega and has clothing on his shoulders and his sandals and rings are in his hands, he and all of them become impure immediately. If he was wearing his clothes and his sandals were on his feet and his rings were in his hands, he becomes impure immediately, and they are pure until he stays there long enough to eat half a loaf of bread, wheat bread and not barley bread, while leaning and eating with a condiment.

מִי שֶׁנִּכְנַס לְבַיִת הַמְנֻגָּע וְכֵלָיו עַל כְּתֵפוֹ וְסַנְדָּלָיו וְטַבְּעוֹתָיו בְּיָדָיו, הוּא וָהֵן טְמֵאִין מִיָּד. הָיָה לָבוּשׁ בְּכֵלָיו וְסַנְדָּלָיו בְּרַגְלָיו וְטַבְּעוֹתָיו בְּיָדָיו, הוּא טָמֵא מִיָּד, וְהֵן טְהוֹרִין עַד שֶׁיִּשְׁהֶה כְדֵי אֲכִילַת פְּרָס. פַּת חִטִּין וְלֹא פַת שְׂעֹרִים, מֵסֵב וְאוֹכְלָן בְּלִפְתָּן: