Tosefta for Demai 7:1
הַמַּזְמִין אֶת חֲבֵרוֹ שֶׁיֹּאכַל אֶצְלוֹ, וְהוּא אֵינוֹ מַאֲמִינוֹ עַל הַמַּעַשְׂרוֹת, אוֹמֵר מֵעֶרֶב שַׁבָּת, מַה שֶּׁאֲנִי עָתִיד לְהַפְרִישׁ מָחָר, הֲרֵי הוּא מַעֲשֵׂר, וּשְׁאָר מַעֲשֵׂר סָמוּךְ לוֹ, זֶה שֶׁעָשִׂיתִי מַעֲשֵׂר עָשׂוּי תְּרוּמַת מַעֲשֵׂר עָלָיו, וּמַעֲשֵׂר שֵׁנִי בִּצְפוֹנוֹ אוֹ בִדְרוֹמוֹ, וּמְחֻלָּל עַל הַמָּעוֹת:
If one invites his friend to eat at his home and the friend does not trust him with regards to tithes, on the day before Shabbat he says, "That which I am going to separate tomorrow is [part of the] tithe, and the rest of the tithe will be next to it. That which I have designated as [part of the] tithe, the <i>Terumat Ma'aser</i> [a portion of the tithes that is given to the priest] is designated upon it. And <i>Ma'aser Sheni</i> [second tithe, must be eaten in Jerusalem] is on its north or south, and is hereby unconsecrated by [transferring its consecration to] coins."