It is narrated from Sa'id bin al-Musayyib (may Allah have mercy on him) that when Sayyidah Hafsah (may Allah be pleased with her) was widowed after the death of her husband, and Sayyiduna Uthman (may Allah be pleased with him) was also left alone due to the death of Sayyidah Ruqayyah (may Allah be pleased with her), Sayyiduna Umar (may Allah be pleased with him) passed by Sayyiduna Uthman (may Allah be pleased with him) and asked whether he had any inclination to marry Hafsah, as her waiting period ('iddah) had also been completed; but he gave no reply. Then Sayyiduna Umar (may Allah be pleased with him) came to the Prophet (peace and blessings be upon him) and mentioned this matter, and he (peace and blessings be upon him) said: "I will marry Hafsah, and I will marry Uthman to her sister (Ruqayyah's sister) Umm Kulthum," to which Sayyiduna Umar (may Allah be pleased with him) gladly agreed.
So the Messenger of Allah (peace and blessings be upon him) married Sayyidah Hafsah (may Allah be pleased with her) and married Sayyiduna Uthman (may Allah be pleased with him) to Sayyidah Umm Kulthum (may Allah be pleased with her).
I (Ibn Hajar) say: The basis of this narration is in Sahih al-Bukhari, narrated through Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) from Sayyiduna Umar (may Allah be pleased with him).
Hadith Referenceالمطالب العالية بزوائد المسانيد الثمانية / كتاب النكاح / 1596
Hadith Gradingمحدثین:إسناده صحيح
Hadith Takhrij«حکم الحدیث المطالب العالیہ محققاً تنسیق د. سعد بن ناصر بن عبد العزيز الشَّثري- مکتبہ شاملہ :قال ابن حجر: أَصْلُهُ فِي الصَّحِيحِ مِنْ حَدِيثِ ابْنِ عُمَرَ ، عَنْ عُمَرَ . » «أخرجه المستدرك للحاكم برقم: 6818»