Obedience to His words is what He commanded them first. It was more important that they trust and obey Him than that they follow the rules for presenting sacrifices that only symbolized their obedience and covered their disobedience. His ancient command to obey also contained promises of blessing if they would trust Him and obey. God had promised to adopt Israel into a uniquely intimate relationship with Himself that would be beneficial for the Israelites as He does us when we trust in Him and obey Him. This is what we know as salvation. Lu 6:46 “But why do you call Me ‘Lord, Lord,’ and do not do the things which I say? Do we really know the Lord? If so our lives will show it by our obedience to Him.
But this thing commanded I them, saying, Obey my voice, and I will be your God, and ye shall be my people: and walk ye in all the ways that I have commanded you, that it may be well unto you. (Jeremiah 7:23)