Parashas Naso · Passuk 7:14
one gold ladle of 10 shekels, filled with incense;
Chabad.org — English translation + Rashi
Source: Menachos 61a.
English: “One ladle” — the vessel combines what is inside it for [the status of] holiness.
In context: A single vessel holding discrete items of kodashim can unite them for the purposes of impurity and sanctity.
Custom
Chazal derive from the ladle that a vessel unifies its contents with respect to sacred status.