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.

حَدَّثَنَا الرَّبِيعُ بْنُ نَافِعٍ، حَدَّثَنَا مُعَاوِيَةُ، - يَعْنِي ابْنَ سَلاَّمٍ - عَنْ زَيْدٍ، - يَعْنِي ابْنَ سَلاَّمٍ - أَنَّهُ سَمِعَ أَبَا سَلاَّمٍ، يَقُولُ حَدَّثَنِي عُبَيْدُ اللَّهِ بْنُ سَلْمَانَ، أَنَّ رَجُلاً، مِنْ أَصْحَابِ النَّبِيِّ ﷺ حَدَّثَهُ قَالَ لَمَّا فَتَحْنَا خَيْبَرَ أَخْرَجُوا غَنَائِمَهُمْ مِنَ الْمَتَاعِ وَالسَّبْىِ فَجَعَلَ النَّاسُ يَتَبَايَعُونَ غَنَائِمَهُمْ فَجَاءَ رَجُلٌ حِينَ صَلَّى رَسُولُ اللَّهِ ﷺ فَقَالَ يَا رَسُولَ اللَّهِ لَقَدْ رَبِحْتُ رِبْحًا مَا رَبِحَ الْيَوْمَ مِثْلَهُ أَحَدٌ مِنْ أَهْلِ هَذَا الْوَادِي قَالَ " وَيْحَكَ وَمَا رَبِحْتَ " . قَالَ مَا زِلْتُ أَبِيعُ وَأَبْتَاعُ حَتَّى رَبِحْتُ ثَلاَثَمِائَةِ أُوقِيَّةٍ فَقَالَ رَسُولُ اللَّهِ ﷺ " أَنَا أُنَبِّئُكَ بِخَيْرِ رَجُلٍ رَبِحَ " . قَالَ مَا هُوَ يَا رَسُولَ اللَّهِ قَالَ " رَكْعَتَيْنِ بَعْدَ الصَّلاَةِ " .