To the debtor when his debt is settled

بارَكَ اللهُ لَكَ في أَهْلِكَ وَمالِك، إِنَّما جَـزاءُ السَّلَفِ الْحَمْدُ والأَداء

May Allah bless you in your family and your wealth, surely the reward for a loan is praise and returning (what was borrowed).

An-Nasa'i, 'Amalul-Yawm wal-Laylahp. 300, Ibn Majah 2/809. See also Al-Albani, Sahih Ibn Majah2/55.