Reference for Demai 4:4

מִי שֶׁקָּרָא שֵׁם לִתְרוּמַת מַעֲשֵׂר שֶׁל דְּמַאי וּלְמַעְשַׂר עָנִי שֶׁל וַדַּאי, לֹא יִטְּלֵם בְּשַׁבָּת. וְאִם הָיָה כֹהֵן אוֹ עָנִי לְמוּדִים לֶאֱכֹל אֶצְלוֹ, יָבֹאוּ וְיֹאכְלוּ, וּבִלְבַד שֶׁיּוֹדִיעֵם:

If one designated the <i>Terumat Ma'aser</i> of <i>Demai</i> or the poor man's tithe of produce that has certainly not been tithed, he should not separate them [to give to a priest or poor person] on Shabbat. If a priest or a poor person was in the habit of eating at his home, they can come and eat as long as he informs them.

Jastrow