Tosefta for Bekhorot 62:39

[With respect to] the daughter of an am ha'aretz who marries a chaver, [or] the [former [?]] wife of an am ha'aretz who marries a chaver, [or] the servant of an am ha'aretz who is sold to a chaver, they [all] need to accept [the yoke of being a chaver] at the beginning (see Avodah Zarah 39a:17). The daughter of an am ha'aretz who marries a chaver, the wife of an am ha'aretz who marries a chaver, and the servant of an am ha'aretz who is sold to a chaver, behold, they are presumed [to maintain the strictures of a chaver] until they are suspected [of not doing so] (see ibid.). Rabbi Shimon ben Elazar (אלעזר not אליעזר) says, they need to accept it upon themselves at the beginning, and moreover Rabbi Shimon ben Elazar said in the name of Rabbi Meir (see Bekh. 31b:18), it so happened that there was a woman who married a chaver and who would tie tefillin on his hand, and she married a tax collector, and she would tie tax seals on his hand. The son of a chaver that was learning [presumably, a craft] at the home of an am ha'aretz, a servant of a chaver that was learning at the home of an am ha'aretz, behold, they are [nonetheless] presumed to [maintain the strictures of a chaver] until they are suspected. The son of an am ha'aretz who was learning at the home of a chaver, the worker of an am ha'aretz who was learning at the home of a chaver, whenever they're at his (i.e., the chaver's) house, behold, they are like a chaver. [But once they] leave from his home, behold, they are like an am ha'aretz.