Therefore

"For that reason"

my words

Here "words" refers to what Jesus says. (See: rc://en/ta/man/translate/figs-metonymy)

Jesus compares those who obey his words to a person who builds his house where nothing can harm it. (See: rc://en/ta/man/translate/figs-simile)

This is the bedrock below the topsoil and clay, not a large stone or boulder above the ground.

This can be stated in active form. AT: "he built it" (See: rc://en/ta/man/translate/figs-activepassive)