Related על ברכות 40:12

Women, slaves and children are exempt [from saying Birkat Hamazon (Grace After Meals)], and they cannot absolve many [people, who include men] from their obligation [of saying Birkat Hamazon]. In reality, they (i.e. the Rabbis) said that a woman can say [Birkat Hamazon] for her husband, a son can say [Birkat Hamazon] for his father, [and] a slave can say [Birkat Hamazon] for his master.