Ibn 'Umar said:

"The Prophet (ﷺ) summoned a cupper, so he cupped him. Then he asked him: “How much is your tax?” He said: “Three measures of grain,” so he reduced his tax by one measure and gave him his fee.”

حَدَّثَنَا هَارُونُ بْنُ إِسْحَاقَ، قَالَ‏:‏ حَدَّثَنَا عَبْدَةُ، عَنِ ابْنِ أَبِي لَيْلَى، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، أَنَّ النَّبِيَّ صلى الله عليه وسلم، دَعَا حَجَّامًا فَحَجَمَهُ وَسَأَلَهُ‏:‏ كَمْ خَرَاجُكَ‏؟‏ فَقَالَ‏:‏ ثَلاثَةُ آصُعٍ، فَوَضَعَ عَنْهُ صَاعًا وَأَعْطَاهُ أَجْرَهُ‏.‏