Mishnah, N’darim 49b
ר׳ יהודה כד אזיל לבי מדרשא שקיל גולפא על כתפיה, אמר: גדולה מלאכה שמכבדת את בעליה. רבי שמעון שקיל צנא על כתפיה, אמר: גדולה מלאכה שמכבדת את בעליה.
Rabbi Yehuda used to go into the beit midrash (house of study) carrying a pitcher on his shoulders. He would say, “Great is work, as it gives honor to the one who does it.” Rabbi Shimon would carry a basket on his shoulders, and would say, “Great is work, as it gives honor to the one who does it."
As cited in Rabbi Jill Jacobs, There Shall Be No Needy: Pursuing Social Justice through Jewish Law & Tradition (Woodstock, VT: Jewish Lights Publishing, 2010), 99.