Umm Salamah (RA)

After Zaynab Um ul-Masakeen the Prophet (PBUH) married Um Salamah also known as Hind bint Umayyah, also a widow, in 4AH.
It is said that she was the most intelligent and wise of all the wives of the Prophet. She was born 28 years before hijra. She too was a widow who had been married to Abu Salama and had emigrated to Abyssinia with him, being forced by the Quraysh to leave her young son behind. Out of her immense love for Abu Salamah she asked for a mutual covenant that even after one of them die the other would not remarry. However Abu Salamah in his great wisdom made a supplication, "O Allah! grant Um Salamah after me a man, who is better than me, one who will cause her no sadness and no hurt".
She died during the reign of Yazid I in 59/678 and was the last of the wives of the Prophet (PBUH) to pass away.