Volume 3 · Book 35 · Hadith 453
Narrated 'Aisha: Allah's Apostle bought some foodstuff (barley) from a Jew on credit and mortgaged his iron armor to him (the armor stands for a guarantor).
— Sahih Bukhari, Volume 3, Book 35: Sales in which a Price is paid for Goods to be Delivered Later (As-Salam), Hadith #453