Narrated Muhammad bin Al-Mujalid
`Abdullah bin Shaddad and Abu Burda sent me to `Abdullah bin Abi `Aufa and told me to ask `Abdullah whether the people in the lifetime of the Prophet (ﷺ) used to pay in advance for wheat (to be delivered later). `Abdullah replied, "We used to pay in advance to the peasants of Sham for wheat, barley and olive oil of a known specified measure to be delivered in a specified period." I asked (him), "Was the price paid (in advance) to those who had the things to be delivered later?" `Abdullah bin `Aufa replied, "We did not use to ask them about that." Then they sent me to `Abdur Rahman bin Abza and I asked him. He replied, "The companions of the Prophet (ﷺ) used to practice Salam in the lifetime of the Prophet; and we did not use to ask them whether they had standing crops or not."
Narrated Abu Bakhtari at-Tai
I asked Ibn `Abbas about Salam for (the fruits of) date-palms. He replied "The Prophet (ﷺ) forbade the sale a dates on the trees till they became fit for eating and could be weighed." A man asked what to be weighed (as the dates were still on the trees). Another man sitting beside Ibn `Abbas replied, "Till they are cut and stored." Narrated Abu Al-Bakhtari: I heard Ibn `Abbas (saying) that the Prophet (ﷺ) forbade... etc. as above.