Sahih Bukhari Volume 3, Book 34, Hadith Number 411.

Narated By Ibn ‘Umar : I was with the Prophet while he was eating spadix. He said, “From the trees there is a tree which resembles a faithful believer.” I wanted to say that it was the date palm, but I was the youngest among them (so I kept quiet). He added, “It is the date palm.” Shuraih told the weavers, “You are permitted to follow your own conventions to solve your problems (it is legal for you to stick to your traditions in bargain).”

Narrated ‘Abdul Wahab: Aiyub said: Muhammad said, “There is no harm in selling for eleven what you buy for ten, and you are allowed to take a profit for expenses.”

The Prophet told Hind, “Take what is reasonable and sufficient for you and your sons.” Allah says: Whoever is poor, can eat (from the orphan’s property) reasonably (according to his labors).

Al-Hasan hired a donkey from ‘Abdullah bin Mirdas and asked him about the hire. The latter replied that it was for two Daniqs (a Daniq equals 116th Dirham). So Al-Hasan rode away. Another time, Al-Hasan came to ‘Abdullah bin Mirdas and asked him to hire the donkey to him and rode away without asking him about the hire, but he sent him half a Dirham.