Ubaydullah bin Salman (may Allah have mercy on him) says that one of the Companions of the Prophet (peace and blessings be upon him) related: When we conquered Khaybar, they took out their spoils, goods and captives and so on, and the people began selling their spoils. A man came and said: O Messenger of Allah! Today I have made such a profit that no one in this valley will have made more than me. He (peace and blessings be upon him) said: "Woe to you! What profit have you made?" He said: I kept on selling and buying until I made a profit of three hundred uqiyah. The Messenger of Allah (peace and blessings be upon him) said: "I will tell you about the man who made a better profit." He said: O Messenger of Allah! What is it? He (peace and blessings be upon him) said: "Two rak'ahs after the prayer."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قسم الفيء والغنيمة / 12909