Making parent work hard for his benefit:
One who makes his father [or mother] perform hard labor [i.e. grind flour in a mill] in order to save his parent from an even more difficult labor, and the child speaks appealingly to his father’s heart, and shows him that his intent is for his best, until his father agrees to the labor [i.e. to grind in the mill], then the child inherits a portion in the world to come.
 Rama 240:4; Kiddushin 31a-b; Yerushalmi Kiddushin 1:7; Encyclopedia Talmudit Erech Kibud Av Vaeim Vol. 26 p. 381