The Prophet ﷺ borrowed forty thousand from me. When some wealth came to him, he handed it over to me and said, "May Allah bless you in your family and your wealth. The reward for a loan is gratitude and repayment."
حدثنا عمرو بن علي قال حدثنا عبد الرحمن عن سفيان
استقرض مني النبي ﷺ أربعين ألفا فجاءه مال فدفعه إلي وقال بارك الله لك في أهلك ومالك إنما جزاء السلف الحمد والأداء
Sourcing, hasan. Ibn Majah narrated it in his chapter on debts, in the section on good repayment of debt, hadith 2424, from the hadith of Ismail bin Ibrahim, with this wording. It is also found in Kubra, hadith 6280, and Iraqi graded it hasan in Ithaf Sadat Muttaqin (5/114).