'Observe' in the Bible

Only be strong and very courageous {to observe diligently the whole law} that Moses my servant commanded you. Do not turn aside from it, [to] the right or left, so that you may succeed {wherever you go}.

The scroll of this law will not depart from your mouth; you will meditate on it day and night so that {you may observe diligently all that is written} in it. For then you will succeed [in] your ways and prosper.

Only be very careful to observe the commandment and law that Moses Yahweh's servant commanded you, to love Yahweh your God, to walk in all his ways, to keep his commandments, to hold fast to him, and to serve him with all your heart and with all your soul."

Be very strong to observe carefully all that is written in the scroll of the law of Moses so as not to turn aside from it, [to] the right or left,