An-Nisa 4:129

Walan tastateeAAoo an taAAdiloobayna annisa-i walaw harastum falatameeloo kulla almayli fatatharooha kalmuAAallaqatiwa-in tuslihoo watattaqoo fa-inna Allaha kanaghafooran raheema

And you will never be able to be equal [in feeling] between wives, even if you should strive [to do so]. So do not incline completely [toward one] and leave another hanging. And if you amend [your affairs] and fear Allāh - then indeed, Allāh is ever Forgiving and Merciful.

You shall never be able to maintain real equality between wives, even though you are eager to. So, do not lean totally (towards one) and leave the other as suspended. If you act righteously and fear Allah, then, Allah is Most-Forgiving, Very-Merciful.