'Observe' in the Bible

regularly offering burnt sacrifices to the Lord on the altar for burnt sacrifice, morning and evening, according to what is prescribed in the law of the Lord which he charged Israel to observe.

then thou dost prosper, if thou dost observe to do the statutes and the judgments that Jehovah charged Moses with concerning Israel; be strong and courageous; do not fear, nor be cast down.

“So now in the sight of all Israel, the assembly of the Lord, and in the hearing of our God, observe and follow all the commands of the Lord your God so that you may possess this good land and leave it as an inheritance to your descendants forever.