A man reported,
The Prophet ﷺ said, "Goods being brought to market are not to be intercepted before reaching it, and a town-dweller is not to sell on behalf of a desert-dweller. Whoever buys a sheep or a she-camel whose udder has been bound up to make her appear to give more milk" — Shuba said, "He only mentioned a she-camel once" — "has the better of two choices after milking her. If he returns her, he must return with her a saa of food."Hakam said, "Or he said, a saa of dates."
Azami 5886
Sahihعن رجل من أصحاب النبي ﷺ
عن النبي ﷺ أنه قال: لا يتلقى جلب، ولا يبع حاضر لباد، ومن اشترى شاة مصراة أو ناقة- قال شعبة: إنما قال: ناقة مرة واحدة-فهو فيها بآخر النظرين إذا هو حلب، إن ردها رد معها صاعا من طعام. قال الحكم: أو قال: صاعا من تمر.
Ahmad (18819) and Bayhaqi (5/319) both narrated it through the hadith of Shubah, from Hakam, from Abdul-Rahman bin Abu Layla, from a man among the companions of the Prophet ﷺ, who mentioned it. Its chain of transmission is sahih, and the fact that the companion is unidentified does not weaken it, as is well known. His statement, "a sa of food, or a sa of dates," reflects uncertainty on the part of one of the narrators, not that it was meant as a choice between the two, so that it accords with the established hadiths. This is what Bayhaqi said. Among the companions, Abdullah bin Masud 
issued a ruling in accordance with this.