This is a superscription that tells about the psalm. Some scholars say that this is part of the scripture and some say that it is not. (See "What are Superscriptions in Psalms" in [Introduction to Psalms](../front/intro.md).)
The author's sadness is spoken of as if it were a container. His sadness comes from the bottom of the container. Sadness is often spoken of as being a container that fills from the top to the bottom. Alternate translation: "Because I am very sad, I" (See: [[rc://en/ta/man/jit/figs-metaphor]])