Beitza 1:10-2:1

Beitzah 1:10

One may send gifts of clothes on yom tov whether they are sewn (and therefore wearable) or unsewn (and not yet wearable); one may even send clothes that contain shaatnez (which would be prohibited to wear) – all of these are permitted so long as it is for the needs of yom tov. (Even if a garment can’t be worn, it may have other uses as a blanket or a cushion.) One may not send a hobnail sandal (which is considered dangerous in crowded spaces) or an unsewn shoe (which is completely unusable). Rabbi Yehuda says that one may not send a white (i.e., undyed) shoe because it requires a professional craftsman’s touch. The general rule is that one may send whatever can be used on yom tov.

Beitzah 2:1

If yom tov falls on Friday, one may not start cooking for Shabbos on yom tov but one may cook on yom tov and use the leftovers for Shabbos. One prepares a cooked item before yom tov and relies on this to permit continuing to prepare for Shabbos over the course of yom tov (i.e., an eiruv tavshilin). Beis Shammai say that one must prepare two items before yom tov, while Beis Hillel require only one item. They agree that a fish cooked with egg on it counts as two items. If the eiruv tavshilin is eaten or lost, he may not prepare on yom tov for Shabbos but so long as any of it remains, he may rely upon it.