It is reported about Sayyiduna Ammar bin Yasir (may Allah be pleased with him) that whenever he heard what people said about the Prophet's (peace and blessings be upon him) marriage to Sayyidah Khadijah (may Allah be pleased with her), he would say: I know more than anyone about the Prophet's (peace and blessings be upon him) marriage to this lady. In the time of Jahiliyyah I was a close companion of the Prophet (peace and blessings be upon him). One day I was going along with the Prophet (peace and blessings be upon him) when we passed by the sister of Sayyidah Khadijah (may Allah be pleased with her), who was in a leather tent of hers. She called me, and I went over to her while the Prophet (peace and blessings be upon him) stopped there. That lady said: "Is your companion (that is, the Prophet (peace and blessings be upon him)) interested in marrying Khadijah (may Allah be pleased with her)?" I told the Prophet (peace and blessings be upon him) about it, and he said: "Yes, by my life." I went back to that lady and told her what the Prophet (peace and blessings be upon him) had said. That lady said: "Come to us tomorrow morning." The next day we went to those people and found that they had slaughtered a cow, had dressed Sayyidah Khadijah's (may Allah be pleased with her) father in a robe and had set up a tent there. I spoke with the brother of Sayyidah Khadijah (may Allah be pleased with her), and her brother spoke with her father. I told him about the Messenger of Allah and his standing, and that the Prophet (peace and blessings be upon him) had asked that he marry Sayyidah Khadijah (may Allah be pleased with her) to him. So they married him to her. Those people had food prepared from the cow and we ate from it. Then Sayyidah Khadijah's (may Allah be pleased with her) father went to sleep. When he woke up, he asked: "Where has this robe come from, why has this tent been set up, and what is this food for?" That daughter of his who had spoken with Sayyiduna Ammar (may Allah be pleased with him) told him: "This robe was put on you by Muhammad bin Abdullah, your son-in-law, and this cow he gave you as a gift; we slaughtered it when you married Sayyidah Khadijah (may Allah be pleased with her) to him." That man denied that he had arranged this marriage. He went out from there and came to the Hatim. When Banu Hashim came, the man asked: "Where is that man of yours about whom you claim that I married him?" When the man saw the Prophet (peace and blessings be upon him) and the Prophet (peace and blessings be upon him) looked at him, the man said: "If I have already married him, fine; otherwise I marry him now."
Al-Tabarani and al-Bazzar recorded it; its chain contains Umar bin Abi Bakr al-Mu'ammali, who is matruk (abandoned).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب المناقب / 15265