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."