891. The Wine for Kiddush
Shabbos 29:13
If one who is eating finishes his meal as Shabbos begins, he should bentch first and then recite kiddush on a different cup of wine. One does not bentch and recite kiddush on the same cup because two mitzvos should not be performed using the same cup; kiddush and bentching are both mitzvos commanded in the Torah.
Shabbos 29:14
Kiddush may be only recited over wine that is fit for use as a libation on the altar. Therefore, if one mixed even a single drop of honey or yeast the size of a mustard seed into a barrelful of wine, kiddush may not be recited over it. This is the universal position followed in western lands but there is an opinion that permits one to recite kiddush over such wine. According to this second opinion, “fit for use as a libation on the altar” is only meant to exclude wine with an unpleasant odor, that was left uncovered or that was cooked. Kiddush may not be recited on any wine such as those.