John Wesley on Genesis 29:31

When the Lord saw that Leah was hated - That is, loved less than Rachel, in which sense it is required that we hate father and mother, in comparison with Christ, Luke 14:26, then the Lord granted her a child, which was a rebuke to Jacob for making so great a difference between those he was equally related to; a check to Rachel, who, perhaps insulted over her sister upon that account; and a comfort to Leah, that she might not be overwhelmed with the contempt put upon her.