(Mishnah): How (do we find that taking the item makes the acquisition)? If he took the produce but had not yet given the money, he cannot retract.

If he gave the money but had not yet taken the produce, he can still retract, but they said that 'the One who punished the generation of the Great Flood will punish one who does not stand by his word.'

R. Shimon: Whoever has the money has the upper hand. (i.e. if the buyer had paid but had not taken the produce, the seller can retract since he has the money, but the buyer cannot.)

(Gemara) - R. Acha: The pasuk states (Bereishis 6, 13), "for the land was filled with chamas before them''. What does chamas refer to? A merchant would take out a box full of Turmasin beans. The city people would come out and each would steal one bean, which was less than the value of a peruta, knowing that the judges would not allow such a minor claim to be brought to court.

R. Chiya bar Vava: The word 'rabah' - 'great', is used both in the pasuk that speaks about the sins of the generation of the flood and about the sins of the people of Sedom and Amora. This teaches that the deeds of the people of the flood were like those of Sedom.

R. Chanina: The halachah follows R. Shimon. This ruling was not agreed upon by all of the Amoraim.

Rav Yirmiyah citing Rav: There was such a case and Rebbi ruled like R. Shimon.