It is narrated from Sayyiduna Jabir (may Allah be pleased with him) that he heard the Prophet (peace and blessings be upon him) forbidding the selling of dates by estimation. He was saying: "Tell me, if the dates are ruined, what will you do? Do you want to consume your brother's wealth unjustly?"
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 15239
Hadith Gradingحکم دارالسلام:حديث صحيح دون قوله: « ينهى عن الخرص » تفرد به ابن لهيعة، وهو سيئ الحفظ