When should a mezuman use a cup of wine?

Hi,

There is an ancient practice of having the leader of a mezuman conclude the birkat hamazon blessing after meals with a blessing upon a cup of wine [or grape juice] (kos shel berachah). This is not considered obligatory; indeed, today some consider it less than appropriate because our mezuman is not a true mezuman. The original form of mezuman involved the leader reciting birkat hamazon on behalf of the listeners, and we have each individual recite birkat hamazon independently.

Some particularly have the leader of the mezuman recite the concluding blessing upon a cup on Shabbat or Yom Tov. Since this is a way to beautify the mitzvah, it is most appropriate for a beautiful day - Shabbat and Yom Tov.

(Rivivot Ephraim 1:150:6)

Have a great day,
Mordechai

Washing out the cup under the chuppah

Hi,

Normally, a cup used to hold wine [or grape juice] for a special mitzvah [kos shel berachah] must be washed out, as a pre-requisite for the mitzvah. However, under the chuppah at a wedding it is common to use the same cup for both the initial kiddushin stage and then again for the sheva berachot of nisuin, adding wine in between. It may not be necessary to wash out the cup in between, because wine is intentionally left in the cup after the first berachah, for use with the second berachah, and so it has not lost the identity associated with the initial washing.

(Rivivot Ephraim 1:150:5)

Have a great day,
Mordechai

Handing over the cup

Hi,

Often, the leader of a ritual mezuman for the birkat hamazon blessing after eating will conclude birkat hamazon with a blessing upon a cup of wine. In such a case, there is a popular practice of having someone hand the leader the full cup of wine. The idea behind this may be to share the performance of the mitzvah with others.

It would seem that this should be done for other cups used with mitzvot [kos shel berachah], but the practice is not widespread.

(Rivivot Ephraim 1:150:3)

Have a great day,
Mordechai

A full cup

Hi,

When a mitzvah requires a blessing on a cup of wine, such as Sheva Berachot, we require that the cup be filled to the top.

(Rav Moshe Feinstein, Igrot Moshe Orach Chaim 4:70:10)

[I sense that "full" is defined based on whether people who see it call it "full", rather than a particular measure of distance from the top, but I cannot prove this.]

Have a great day,
Mordechai