Sahih Muslim Book 023, Hadith Number 5093.
Chapter : The merit of vinegar as a condiment.
Jabir b. 'Abdullah reported that Allah's Apostle (may peace be upon him) asked his family for condiment. They (the members of his household) said: We have nothing with us but vinegar. He asked for it, he began to eat it, and then said: Vinegar is a good condiment, vinegar is a good condiment.