It is narrated from Ibn al-Aqmar that the cavalry made a raid in Syria (al-Sham). The (Arab) horses caught up (with the enemy) the same day, and the kawadin (heavy non-Arab horses) caught up at forenoon. In command of the cavalry was al-Mundhir bin Abi Himmasah al-Hamdani. He gave the (Arab) horses preference over the kawadin and said: I will not treat what caught up the same as what did not catch up. This reached Sayyiduna Umar bin al-Khattab (may Allah be pleased with him), and he said: "May his mother be bereft of al-Wadi'i! She has indeed borne a true man. Carry it out as he said."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قسم الفيء والغنيمة / 12885