Selling what has not yet been taken into possession

Sa'id bin al-Musayyib narrates: I heard Sayyiduna Uthman Ghani (may Allah be pleased with him) say while delivering a sermon on the pulpit: "I used to buy dates from a clan of the Jews who were called Banu Qaynuqa', and I would sell them at a profit. News of this reached the Prophet (peace and blessings be upon him), and he said: 'O Uthman! When you buy, take it by measure, and when you sell, give it by measure.'" (Allamah al-Haythami says:) I say:
Ibn Majah recorded this narration in abridged form.
Ahmad recorded it, and its chain is hasan (good).

Sayyiduna Umar (may Allah be pleased with him) narrates that the Prophet (peace and blessings be upon him) said: "Whoever buys foodstuff should not sell it on until he has taken full possession of it (by measure)."
Abu Ya'la, al-Tabarani in al-Mu'jam al-Kabir, and al-Bazzar recorded it; its chain contains Abdullah bin Umar al-Umari, who has been criticised, though he has also been declared trustworthy.

Sayyiduna Abu Hurayrah (may Allah be pleased with him) reports about the Prophet (peace and blessings be upon him) that he forbade the sale of foodstuff until the two sa' (measures, of both parties) have been applied to it, so that any excess goes to its owner and any shortfall is borne by him. (Allamah al-Haythami says:) I say: The hadith of Sayyiduna Abu Hurayrah (may Allah be pleased with him) in the "Sahih" is about the prohibition of selling foodstuff before measuring it.
Al-Bazzar recorded it; its chain contains Muslim bin Abi Muslim al-Jarmi, and I have not found anyone who has written his biography; the rest of its narrators are the narrators of the Sahih.