Riyad as-Salihin
The Book of Jihad
كتاب الجهاد
Chapter 240: Excellence of Fair Bargaining and Matters Relation to it
Jabir (May Allah be pleased with him) reported
The Prophet (ﷺ) purchased a camel from me and weighed more than its price.[Al-Bukhari and Muslim].
Abu Safwan Suwaid bin Qais (May Allah be pleased with him) reported
Makhramah Al-'Abdi and I procured some drapery from Hajar and brought them to Makkah. The Prophet (ﷺ) came and bargained with us for some trousers and we sold them to him. We had a person who weighed the cloth in order to fix the price. The Prophet (ﷺ) said to him, "Weigh and add a little to it."[Abu Dawud and At- Tirmidhi].