en_tn_lite_do_not_use/psa/119/034.md

keep your law

"obey your law"

I will observe it with all my heart

"I will surely observe your law" or "I am completely committed to doing what it says"

with all my heart

This is an idiom. Alternate translation: "with all my being" or "with everything in me" or "sincerely" (See: rc://en/ta/man/jit/figs-idiom)