One can donate wine, but one cannot donate oil; [these are] the words of R’ Akiva. R’ Tarfon says: One can donate oil. Said R’ Tarfon: Just as we find concerning wine that it comes as an obligation or as a donation, so too, oil comes as an obligation or as a donation. R’ Akiva said to him: No. If this is said of wine, it is because it is brought as an obligation on its own. Can you say [the same] of oil which is not brought as an obligation on its own? Two [people] cannot donate one issaron, but they can donate an olah-offering and a shelamim-offering, and with a bird, even a single bird.