בְּזֵעַ֤ת אַפֶּ֙יךָ֙ תֹּ֣אכַל לֶ֔חֶם עַ֤ד שֽׁוּבְךָ֙ אֶל־הָ֣אֲדָמָ֔ה כִּ֥י מִמֶּ֖נָּה לֻקָּ֑חְתָּ כִּֽי־עָפָ֣ר אַ֔תָּה וְאֶל־עָפָ֖ר תָּשֽׁוּב׃
C’est à la sueur de ton visage que tu mangeras du pain, — jusqu’à ce que tu retournes à la terre d’où tu as été tiré: car poussière tu fus, et poussière tu redeviendras!"
Mishnah Nedarim
He who vows not to wear garments is permitted sack-cloth, curtain, and blanket wrapping. If he says, “Konam, if wool comes upon me,” he may cover himself with wool shearings; [Konam] if flax comes upon me”, he may cover himself with stalks of flax. Rabbi Judah says: It all depends upon the person who vows, [thus:] if he was bearing a burden [with wool or flax] and perspires and had bad odor, and he said “Konam if wool or flax come upon me,” he may wear them, but not throw them [as a bundle] over his back.