Sahih Bukhari · Hadith 2158

حدثنا الصلت بن محمد، حدثنا عبد الواحد، حدثنا معمر، عن عبد الله بن طاوس، عن أبيه، عن ابن عباس رضى الله عنهما قال قال رسول الله صلى الله عليه وسلم ‏"‏ لا تلقوا الركبان ولا يبيع حاضر لباد ‏"‏‏.‏ قال فقلت لابن عباس ما قوله لا يبيع حاضر لباد قال لا يكون له سمسارا‏.‏

Narrated Tawus: Ibn `Abbas said, "Allah's Apostle said, 'Do not go to meet the caravans on the way (for buying their goods without letting them know the market price); a town dweller should not sell the goods of a desert dweller on behalf of the latter.' I asked Ibn `Abbas, 'What does he mean by not selling the goods of a desert dweller by a town dweller?' He said, 'He should not become his broker.' "

Gradings are classical jarḥ-wa-taʿdīl, name-matched to a rijāl index (not individually re-verified).