Kaab demanded from Ibn Abu Hadrad the repayment of a debt he owed him, and this took place in the mosque. Their voices grew loud until the Messenger of Allah ﷺ heard them from inside his house. He came out to them, drawing back the curtain of his chamber, and called out, "Kaab."Kaab replied, "At your service, Messenger of Allah."The Prophet ﷺ said, "Reduce this much from your debt," gesturing to indicate half.Kaab said, "I have done so, Messenger of Allah."The Prophet ﷺ then said to Ibn Abu Hadrad, "Get up and pay him."
أنه تقاضى ابن أبي حدرد دينا كان له عليه في المسجد، فارتفعت أصواتهما، حتى سمعها رسول الله ﷺ- وهو في بيته-، فخرج إليهما حتى كشف سجف حجرته، فنادى: يا كعب. قال: لبيك يا رسول الله قال: ضع من دينك هذا. وأومأ إليه أي الشطر. قال: لقد فعلت يا رسول الله، قال: قم فاقضه.
Bukhari narrated it in the Prayer chapter (457), and Muslim in the Sales/Irrigation chapter (1558), both from the hadith of Uthman bin Umar, who said, "Yunus informed us, from Zuhri, from Abdullah bin Kaab, from Kaab bin Malik," and he related it.