3,447. Tithes and the Shabbos Guest

Hilchos Maaser 9:9

The one separating tithes on Shabbos must whisper his declarations silently. He is not considered to be rendering something fit for use on Shabbos because of his pre-Shabbos condition. When such a condition is made regarding tevel, it may be handled on Shabbos even before he takes the tithes. He focuses on one part of the produce and eats from the rest.

Hilchos Maaser 9:10

If an unlearned person gives someone a cup of wine on Shabbos, that person should say, “What I will leave at the bottom is tithes, and the rest of the tithes are next to it. What I designated as tithes is terumas maaser for the rest that is next to it. The second tithe is at the rim of the cup and its sanctity is transferred to money.” After doing this, he may drink, leaving a volume appropriate for terumas maaser at the bottom.