Ibn Abbas narrated that:
when the Prophet conquered Khaibar, he stipulated that the land, and all the yellow and white, meaning gold and silver belonged to him. The people of Khaibar said to him: “We know the land better, so give it to us so that we may work the land, and you will have half of its produce and we will have half.” He maintained that, he gave it to them on that basis. When the time for the date harvest came, he sent Ibn Rawahah to them. He assesses the date palms, and he said: “For this tree, such and such (amount).” They said: “You are demanding too much of us, O Ibn Rawahah!” He said: “This is my assessment and I will give you half of what I say.” They said: “This is fair, and fairness is what haven and earth are based on.” They said: “We Agree to take (accept) what you say.”

حَدَّثَنَا مُوسَى بْنُ مَرْوَانَ الرَّقِّيُّ، حَدَّثَنَا عُمَرُ بْنُ أَيُّوبَ، عَنْ جَعْفَرِ بْنِ بُرْقَانَ، عَنْ مَيْمُونِ بْنِ مِهْرَانَ، عَنْ مِقْسَمٍ، عَنِ ابْنِ عَبَّاسٍ، أَنَّ النَّبِيَّ ـ ﷺ ـ حِينَ افْتَتَحَ خَيْبَرَ اشْتَرَطَ عَلَيْهِمْ أَنَّ لَهُ الأَرْضَ وَكُلَّ صَفْرَاءَ وَبَيْضَاءَ . يَعْنِي الذَّهَبَ وَالْفِضَّةَ . وَقَالَ لَهُ أَهْلُ خَيْبَرَ نَحْنُ أَعْلَمُ بِالأَرْضِ فَأَعْطِنَاهَا عَلَى أَنْ نَعْمَلَهَا وَيَكُونَ لَنَا نِصْفُ الثَّمَرَةِ وَلَكُمْ نِصْفُهَا . فَزَعَمَ أَنَّهُ أَعْطَاهُمْ عَلَى ذَلِكَ فَلَمَّا كَانَ حِينَ يُصْرَمُ النَّخْلُ بَعَثَ إِلَيْهِمُ ابْنَ رَوَاحَةَ فَحَزَرَ النَّخْلَ وَهُوَ الَّذِي يَدْعُونَهُ أَهْلُ الْمَدِينَةِ الْخَرْصَ فَقَالَ فِي ذَا كَذَا وَكَذَا . فَقَالُوا أَكْثَرْتَ عَلَيْنَا يَا ابْنَ رَوَاحَةَ . فَقَالَ فَأَنَا أَحْزُرُ النَّخْلَ وَأُعْطِيكُمْ نِصْفَ الَّذِي قُلْتُ . قَالَ فَقَالُوا هَذَا الْحَقُّ وَبِهِ تَقُومُ السَّمَاءُ وَالأَرْضُ . فَقَالُوا قَدْ رَضِينَا أَنْ نَأْخُذَ بِالَّذِي قُلْتَ .