RobH_en_tn/psa/119/111.md

I claim your covenant decrees as my heritage forever

The writer always cherishing and obeying God's decrees is spoken of as if the decrees are land or a possession that the writer will inherit. Alternate translation: "Your laws will belong to me forever" or "Your covenant decrees are like a heritage I will keep forever" (See: rc://en/ta/man/translate/figs-metaphor)

they are the joy of my heart

Here "heart" represents the whole person. Alternate translation: "they make me joyful" or "I delight in them" (See: rc://en/ta/man/translate/figs-synecdoche)