en_tn/psa/040/002.md

out of a horrible pit, out of the miry clay

These two metaphors mean the same thing. The writer's danger is spoken of as if it was a deadly pit full of mud. This emphasizes the danger. Alternate translation: "from being trapped in a horrible pit full of sticky mud" (See: rc://en/ta/man/translate/figs-parallelism and rc://en/ta/man/translate/figs-metaphor)

he set my feet on a rock

Here "my feet" refers to the writer, and "a rock" refers a place of safety. Alternate translation: "he provided safety for me" (See: rc://en/ta/man/translate/figs-synecdoche and rc://en/ta/man/translate/figs-metonymy)