Commercial Transactions (Kitab Al-Buyu)
Dawud :: Book 22 : Hadith 3330
Narrated Suwayd ibn Qays:
I and Makhrafah al-Abdi imported some garments from Hajar, and brought them to Mecca. The Apostle of Allah (peace_be_upon_him) came to us walking, and after he had bargained with us for some trousers, we sold them to him. There was a man who was weighing for payment. The Apostle of Allah (peace_be_upon_him) said to him: Weigh out and give overweight.