It is forbidden to meet the caravans on the way (to buy the goods away from the market) Sahih al-Bukhari 2164
Arabic hadith text
حَدَّثَنَا مُسَدَّدٌ، حَدَّثَنَا يَزِيدُ بْنُ زُرَيْعٍ، قَالَ حَدَّثَنِي التَّيْمِيُّ، عَنْ أَبِي عُثْمَانَ، عَنْ عَبْدِ اللَّهِ ـ رضى الله عنه ـ قَالَ مَنِ اشْتَرَى مُحَفَّلَةً فَلْيَرُدَّ مَعَهَا صَاعًا. قَالَ وَنَهَى النَّبِيُّ صلى الله عليه وسلم عَنْتَلَقِّي الْبُيُوعِ.
Translation
Narrated `Abdullah
Whoever buys an animal which has been kept unmilked for a long time, could return it, but has to pay a Sa of dates along with it. And the Prophet (ﷺ) forbade meeting the owners of goods on the way away from the market.