Jabir b. 'Abdullah reported that Allah's Apostle (ﷺ) 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.
حَدَّثَنَا يَحْيَى بْنُ يَحْيَى، أَخْبَرَنَا أَبُو عَوَانَةَ، عَنْ أَبِي بِشْرٍ، عَنْ أَبِي سُفْيَانَ، عَنْ جَابِرِ بْنِ عَبْدِ اللَّهِ، أَنَّ النَّبِيَّ صلى الله عليه وسلم سَأَلَ أَهْلَهُ الأُدُمَ فَقَالُوا مَا عِنْدَنَا إِلاَّ خَلٌّ ‏.‏ فَدَعَا بِهِ فَجَعَلَ يَأْكُلُ بِهِ وَيَقُولُ ‏ "‏ نِعْمَ الأُدُمُ الْخَلُّ نِعْمَ الأُدُمُ الْخَلُّ ‏"‏ ‏.‏
Reference : Sahih Muslim 2052 a
In-book reference : Book 36, Hadith 226
USC-MSA web (English) reference : Book 23, Hadith 5093
  (deprecated numbering scheme)