Hammad bin Zayd حماد بن زيد بن درهم الأزدي الأزرق · Commercial Transactions (Kitab Al-Buyu)

We were with the Messenger of Allah (ﷺ) at the battle of Khaibar. We were selling to the Jews one uqiyah of gold for one dinar. The narrators other than Qutaibah said: "for two or three dinars." Then both the versions agreed. The Messenger of Allah (ﷺ) said: Do not sell gold except with equal weight.

The tradition mentioned above has also been transmitted by Simak (b. Harb) with a different chain of narrators and to the same effect. The first version is more perfect. It does not mention the words "at the current rate".

The Prophet (ﷺ) forbade selling fruits years ahead, and commanded that unforeseen loss be remitted in respect of what is affected by blight. Abu Dawud said: The attribution of the tradition regarding the effect of blight is one-third of the produce to the Prophet (ﷺ) is not correct. This is the opinion of the people of Medina.

We used to employ people to till land for a share of it produce. He then maintained that, one of his uncles came to him and said: The Messenger of Allah (ﷺ) forbade us from a work which beneficial to us. But obedience to Allah and His Apostle (ﷺ) is more beneficial to us. We asked : What is that ? He said: The Messenger of Allah (ﷺ) said: If anyone has land, he should cultivate it, or lend it…

The Prophet (ﷺ) said: If anyone sows in other people's land without their permission, he has no right to any of the crop, but he may have what it cost him.