Shabbos17: 6
הָאֶבֶן שֶׁבְּקֵרוּיָה, אִם מְמַלְאִין בָּהּ וְאֵינָהּ נוֹפֶלֶת, מְמַלְאִין בָּהּ; וְאִם לָאו, אֵין מְמַלְאִין בָּהּ. זְמוֹרָה שֶׁהִיא קְשׁוּרָה בְטָפִיחַ, מְמַלְאִין בָּהּ בַּשַּׁבָּת.
A stone that is in a gourd-shell, if water can be drawn with it without its falling out, we may draw [water] with it; and if not, we may not draw [water] with it. A branch that is tied to a pitcher, we may draw water with it on the Sabbath.