Abu Ma'bad, who was the slave of Sayyiduna Ibn Abbas (may Allah be pleased with them both), reports: Sayyiduna Ibn Abbas (may Allah be pleased with them both) would sell his fruit to his slave before it ripened, and he would say that between a master and his slave there is no usury (riba).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / 10607