Shamar means to keep, guard, watch, observe, or preserve. It appears about 470 times. It describes guarding property, observing commandments, keeping covenant, and protecting people.
Israel is commanded to shamar (keep/observe) God's laws. God keeps covenant and guards His people. Psalm 121 repeats 'the LORD will keep you' six times. Faithfulness involves careful observance — keeping what has been entrusted. Jesus said 'If you love me, keep my commands' (John 14:15).