Basically, the verse says that “obedience is better than sacrifice” (1 Samuel 15:22).
Firstly, we need to define “obedience”. This is simple enough since “obedience” means “keeping/following His Word/Commands”.
Now, doing His commands must also be in accordance to His Principles. For example, charity works are commendable but the Lord clearly states that doing them in “public” merits “no” reward from the Father in Heaven (Matthew 6:1).
That is, obedience involves doing His Word His Way.
The hardest part of obedience is to “not sin anymore”. This is especially difficult since one may often falk prey to many sins. Hence, due to lack of obedience on one’s part, one’s sacrifices may not have the impact if one had stopped sinning completely.
Lastly, obedience is the only way which proves “how much” one loves the Lord since He Himself said, “If you love Me, obey My commands“. (John 14:15).
When we disagree with God, we obey “ourselves” or “others”. Thus, we always “obey” something.