Sforno on Genesis 30:6/ספורנו על בראשית ל׳:ו׳

1דנני אלוקים, G’d was just and fair in not granting me children.

2וגם שמע בקולי, but even so He did accept my prayer.

3ויתן לי בן, someone who will look after me in my old age., seeing he has been born on my knees, i.e. will be raised by me. When Yaakov’s senior wives, Rachel and Leah made such statements, they thereby signaled their agreement to freeing their handmaids who had possessed slave status up until then. They did this by referring to the sons of the handmaids as בנים, children, rather than as עבדים, slaves. If their mothers had been slaves, the children would have to be viewed and treated as slaves. We have proof of this from Exodus 21,4 האשה וילדיה תהיה לאדוניה, “the woman and her children will belong to her master.” This is the reason why these matriarchs did no longer have the mothers of the handmaids’ sons perform menial tasks for them as they did before these women were given to Yaakov to have children with. This was quite different from when Avraham had said to Sarah that Hagar, mother of Ishmael was “in your hand, do to her what you like,” i.e. she continued in her status as slave. They are always listed as בני יעקב, and participate fully in the inheritance, as opposed to a slave who cannot inherit as anything given to him automatically belongs to his master. In the case of Ishmael, the Torah had made sure by saying כי ביצחק יקרא לך זרע “for your (Avraham’s) seed will be perpetuated through Yitzchok, that we would understand that Ishmael was not Avraham’s heir. (21,12)