Muwatta Imam Malik Book of Business Transactions, Hadith 19

Yahya related to me from Malik from Abu'r-Rijal, Muhammad ibn Abdar-Rahman ibn Haritha that his mother, Amra bint Abd ar-Rahman used to sell her fruit and keep some of it aside.
Malik said, "The generally agreed upon way of doing things among us is that when a man sells the fruit of his orchard, he can keep aside up to a third of the fruit, but that is not to be exceeded. There is no harm in what is less than a third."
Malik added that he thought there was no harm for a man to sell the fruit of his orchard and keep aside only the fruit of a certain palm-tree or palm-trees which he had chosen and whose number he had specified, because the owner was only keeping aside certain fruit of his own orchard and everything else he sold.

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ أَبِي الرِّجَالِ، مُحَمَّدِ بْنِ عَبْدِ الرَّحْمَنِ بْنِ حَارِثَةَ أَنَّ أُمَّهُ، عَمْرَةَ بِنْتَ عَبْدِ الرَّحْمَنِ كَانَتْ تَبِيعُ ثِمَارَهَا وَتَسْتَثْنِي مِنْهَا . قَالَ مَالِكٌ الأَمْرُ الْمُجْتَمَعُ عَلَيْهِ عِنْدَنَا أَنَّ الرَّجُلَ إِذَا بَاعَ ثَمَرَ حَائِطِهِ أَنَّ لَهُ أَنْ يَسْتَثْنِيَ مِنْ ثَمَرِ حَائِطِهِ مَا بَيْنَهُ وَبَيْنَ ثُلُثِ الثَّمَرِ لاَ يُجَاوِزُ ذَلِكَ وَمَا كَانَ دُونَ الثُّلُثِ فَلاَ بَأْسَ بِذَلِكَ . قَالَ مَالِكٌ فَأَمَّا الرَّجُلُ يَبِيعُ ثَمَرَ حَائِطِهِ وَيَسْتَثْنِي مِنْ ثَمَرِ حَائِطِهِ ثَمَرَ نَخْلَةٍ أَوْ نَخَلاَتٍ يَخْتَارُهَا وَيُسَمِّي عَدَدَهَا فَلاَ أَرَى بِذَلِكَ بَأْسًا لأَنَّ رَبَّ الْحَائِطِ إِنَّمَا اسْتَثْنَى شَيْئًا مِنْ ثَمَرِ حَائِطِ نَفْسِهِ وَإِنَّمَا ذَلِكَ شَىْءٌ احْتَبَسَهُ مِنْ حَائِطِهِ وَأَمْسَكَهُ لَمْ يَبِعْهُ وَبَاعَ مِنْ حَائِطِهِ مَا سِوَى ذَلِكَ .