Bible did not tell anyone to observe holy week, but christians choose to do so, just to remember the suffering of Jesus Christ. Holy Week is a traditional Christian observance that remembers the final week of Jesus Christ's earthly ministry, including His suffering, death, and resurrection. What matters most from a biblical perspective is not observing a particular week, but sincerely remembering Christ's sacrifice and living in obedience to His teachings every day.
The bible doesn't condemn Christian who observe holy week provided it does go against God's will, provided they do not treat it as a requirement for salvation or place human traditions above God's Word. The apostle Paul taught that believers should respect one another's convictions regarding special days, as long as everything is done to honor the Lord.
"One person considers one day more sacred than another; another considers every day alike. Each of them should be fully convinced in their own mind." Romans 14:5
