Ma'asros2: 7
הַשּׂוֹכֵר אֶת הַפּוֹעֵל לִקְצוֹת עִמּוֹ בִתְאֵנִים, אָמַר לוֹ: ,,עַל מְנָת שֶׁאֹכַל תְּאֵנִים”, אוֹכֵל וּפָטוּר; ,,עַל מְנָת שֶׁאֹכַל אֲנִי וּבְנֵי בֵיתִי”, אוֹ ,,שֶׁיֹּאכַל בְּנִי בִשְׂכָרִי”, הוּא אוֹכֵל וּפָטוּר, וּבְנוֹ אוֹכֵל וְחַיָּב; ,,עַל מְנָת שֶׁאֹכַל בִּשְׁעַת הַקְּצִיעָה וּלְאַחַר הַקְּצִיעָה”, בִּשְׁעַת הַקְּצִיעָה אוֹכֵל וּפָטוּר; וּלְאַחַר הַקְּצִיעָה אוֹכֵל וְחַיָּב, שֶׁאֵינוֹ אוֹכֵל מִן הַתּוֹרָה. זֶה הַכְּלָל: הָאוֹכֵל מִן הַתּוֹרָה פָּטוּר; וְשֶׁאֵינוֹ אוֹכֵל מִן הַתּוֹרָה חַיָּב.
[If] one hires a worker to help him spread figs to dry, [and the worker] said to him, “[I will work for you] on condition that I may eat [of the] figs,” [the worker] may eat [the figs] and is exempt [from tithing them]; [if the worker said,] “On condition that I and the members of my household may eat [figs],” or, “[On condition] that my son may eat [figs] as my wages,” he may eat and is exempt [from tithing the figs], and his son may eat but is obligated [to tithe the figs]; [if the worker stipulates,] “On condition that I may eat [figs] during the spreading and after the spreading,” during the spreading he may eat and is exempt [from tithes]; after the spreading he may eat but is obligated [in tithes], because he is not eating by [sanction of] the Torah.  This is the rule: One who eats by [sanction of] the Torah is exempt [from tithes]; but one who does not eat by [sanction of] the Torah is obligated [in tithes].