It is narrated from Sayyidah Umm Mubashshir (may Allah be pleased with her) that the Prophet (peace and blessings be upon him) proposed marriage to the daughter of al-Bara' bin Ma'rur, and she said: "I made a condition with my husband that I would not marry after him." He (peace and blessings be upon him) said: "That condition is not valid."
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 21729