'Observes' in the Bible

I assure you and most solemnly say to you, if anyone keeps My word [by living in accordance with My message] he will indeed never, ever see and experience death.”

He who observes the day, observes it for the Lord. He who eats, eats for the Lord, since he gives thanks to God; while he who abstains, abstains for the Lord and gives thanks to God.

for once he has looked at himself and gone away, he immediately forgets what he looked like.

But whoever habitually keeps His word and obeys His precepts [and treasures His message in its entirety], in him the love of God has truly been perfected [it is completed and has reached maturity]. By this we know [for certain] that we are in Him:

“And behold, I am coming quickly. Blessed (happy, prosperous, to be admired) is the one who heeds and takes to heart and remembers the words of the prophecy [that is, the predictions, consolations, and warnings] contained in this book (scroll).”