Daf Yomi - Beitzah 36 - Lekavod Shabbos

The Gemara cites the opinion of Rabbi Yitzchak who maintains that a vessel cannot be moved except for the need of an item which that item itself can be moved on Shabbos. We can interpret this statement homiletically to mean that one should not conduct himself on Shabbos in an unbecoming manner, as one should ensure that all his actions are in consonance with the Holy Shabbos.