Al-Matalib al-'Aliyah 3884 — The virtues of Umar bin al-Khattab

It is narrated from a man that Sayyiduna Abu Sufyan (may Allah be pleased with him) came to the Prophet (peace and blessings be upon him) and sat with him, then said: "Have you not considered the matter of your sister-in-law (or close female relative), to whom Umar bin al-Khattab (may Allah be pleased with him) sent a proposal of marriage, but she refused?" The Messenger of Allah (peace and blessings be upon him) said: "What kept her from marrying Umar (may Allah be pleased with him)? There is no man in Madinah, unless he be a prophet, who is more virtuous and better than Umar (may Allah be pleased with him)." (Thabit bin al-Hajjaj said:) I asked the man who narrated this hadith to me: "Was Sayyiduna Abu Bakr al-Siddiq (may Allah be pleased with him) in Madinah at that time?" He replied: "I do not know about that."
This narration is in Musnad al-Harith (Zawa'id al-Haythami); however, one narrator in its chain is unnamed (mubham), and for this reason it is weak in its chain.