Narrated A man from the Companions of the Prophet: Ubaydullah ibn Salman reported on the authority of a man from the Companions of the Prophet ﷺ: When we conquered Khaybar, they (the people) took out their spoils which contained equipment and captives. The people began to buy and sell their spoils. When the Messenger of Allah ﷺ prayed, a man came to him and said: Messenger of Allah, I have gained today so much so that no one gained from this valley. He asked: Woe unto you, how much did you gain? He replied: I kept on selling and buying until I gained three hundred uqiyahs. The Messenger of Allah ﷺ said: I tell you a man who gained better than you. He asked: What is that, Messenger of Allah? He replied! Two rak'ahs (of supererogatory prayer) after the (obligatory) prayer.
Hadith Referenceسنن ابي داود / كتاب الجهاد / 2785
Hadith Gradingالألبانی:ضعيف | زبیر علی زئی:ضعيف, إسناده ضعيف, عبيد اللّٰه بن سلمان مجھول (تق : 4298), و لم يوثقه أحد فيما أعلم, انوار الصحيفه، صفحه نمبر 100
Hadith Takhrij« تفرد بہ أبو داود، (تحفة الأشراف: 15632) (ضعیف) » (اس کے راوی عبیداللہ بن سلمان مجہول ہیں)