Hadrat Abdullah bin Umar (may Allah be pleased with them both) narrates that when Hadrat Hafsah bint Umar (may Allah be pleased with them both), the daughter of Hadrat Umar bin al-Khattab (may Allah be pleased with him), was widowed by the death in Madinah of Khunays bin Hudhafah al-Sahmi (may Allah be pleased with him) (who was a Companion of the Messenger of Allah (peace and blessings be upon him) and had taken part in Badr), Hadrat Umar (may Allah be pleased with him) said: I offered my daughter to Hadrat Uthman bin Affan (may Allah be pleased with him) (that is, proposed marriage to him). I said: "If you wish, I will marry you to Hafsah bint Umar." Hadrat Uthman bin Affan (may Allah be pleased with him) said: "Let me think over my affairs." Hadrat Umar (may Allah be pleased with him) said: I waited for a few days; then Uthman bin Affan (may Allah be pleased with him) met me and said: "I will not marry at present." Hadrat Umar (may Allah be pleased with him) said: I met Hadrat Abu Bakr al-Siddiq (may Allah be pleased with him) and said: "If you wish, I will marry you to Hafsah bint Umar." Hadrat Abu Bakr (may Allah be pleased with him) remained silent and gave me no answer. I felt more grieved inside than I had with Hadrat Uthman bin Affan (may Allah be pleased with him). After a few days the Prophet (peace and blessings be upon him) proposed marriage (to her), and I married her to him (peace and blessings be upon him). Then Abu Bakr (may Allah be pleased with him) met me and said: "Perhaps you were upset when you offered Hadrat Hafsah (may Allah be pleased with them both) to me for marriage and I gave you no answer at all." Hadrat Umar (may Allah be pleased with him) said: "Yes." So Hadrat Abu Bakr (may Allah be pleased with him) said: "Nothing prevented me from answering you when you proposed the marriage, except that I knew that the Messenger of Allah (peace and blessings be upon him) had mentioned Hadrat Hafsah (may Allah be pleased with them both), and I did not want to disclose the secret of the Messenger of Allah (peace and blessings be upon him). Had the Messenger of Allah (peace and blessings be upon him) left her, I would have accepted her."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 13749