Rashi on Genesis 46:19/רש"י על בראשית מ״ו:י״ט

1בני רחל אשת יעקב THE SONS OF RACHEL, JACOB’S WIFE — In the case of all the other wives of Jacob the term אשת “wife” is not mentioned. But the reason is because she was the chief mistress of the household (Genesis Rabbah 73:1).