Mishkat al-Masabih 4222
Umm Hani’ said:
The Prophet came in to visit me and asked whether I had anything. When I replied that I had nothing but some dry bread and vinegar he said, “Produce it; a house in which there is vinegar is not devoid of condiments.” 

Tirmidhi transmitted it, saying this is a hasan gharib tradition.
وَعَن أم هَانِئ قَالَتْ: دَخَلَ عَلَى النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فَقَالَ: «أَعِنْدَكِ شَيْءٌ» قُلْتُ: لَا إِلَّا خُبْزٌ يَابِسٌ وَخَلٌّ فَقَالَ: «هَاتِي مَا أَقْفَرَ بَيْتٌ مِنْ أَدَمٍ فِيهِ خَلٌّ» . رَوَاهُ التِّرْمِذِيُّ وَقَالَ: هَذَا حَدِيثٌ حَسَنٌ غَرِيبٌ