Majma al-Zawaid — Hadith 10251

Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) narrates: On the day of the Conquest of Makkah, the Prophet (peace and blessings be upon him) came to the home of Sayyidah Umm Hani' bint Abi Talib (may Allah be pleased with her). The Prophet (peace and blessings be upon him) was feeling hungry. Sayyidah Umm Hani' (may Allah be pleased with her) said to the Prophet (peace and blessings be upon him): "O Messenger of Allah! Some of my in-laws have taken refuge with me, and Sayyiduna Ali bin Abi Talib (may Allah be pleased with him) is a man who, in matters of Allah Almighty, does not care for the blame of any blamer. I fear that if he learns about my relatives, he will kill them. So decree that whoever enters the house of Umm Hani' will be counted safe, until those people hear the word of Allah." The Prophet (peace and blessings be upon him) granted those people safety and said: "Whomever Umm Hani' has given protection, we too give protection." Then the Prophet (peace and blessings be upon him) asked: "Do you have anything that we may eat?" She said: "I have only a dry piece of bread, and I feel ashamed to present it to you." The Prophet (peace and blessings be upon him) said: "Bring that." Sayyidah Umm Hani' (may Allah be pleased with her) broke it up and put it in water; then she brought salt. The Prophet (peace and blessings be upon him) asked: "Is there any condiment?" Sayyidah Umm Hani' (may Allah be pleased with her) said: "O Messenger of Allah! I have nothing except a little vinegar." The Prophet (peace and blessings be upon him) said: "Bring that and pour it over the food." The Prophet (peace and blessings be upon him) ate it, and then he praised Allah Almighty, and then he said: "Vinegar is an excellent condiment. O Umm Hani', the people of a house in which there is vinegar are not without a condiment."
Al-Tabarani recorded it in al-Mu'jam al-Saghir, and its chain contains a narrator, Sa'dan bin al-Walid, whom I do not know.