I have read authors who think people in the Old Testament were saved by works alone. That people were saved by doing sacrifices, tithing and doing other law-works.
The Old Testament does tell the people of Israel to do sacrifices and various law-works, there is no denying that, and an unwillingness to do them was not a good sign.
But if you read the prophets you will see very clearly that God is not interested in dead animals and religious hoop-jumping; He’s primarily interested in the heart of a person.
Jesus once told a crowd who thought they knew the OT to “go ye and learn what that meaneth, I will have mercy, and not sacrifice.”
Jesus had a problem with the scribes and Pharisees because they “pay tithe of mint and anise and cummin, and have omitted the weightier matters of the law, judgment, mercy, and faith.”
Just going through the motions of obedience, doing the bare requirement of lawful works, is not what God was looking for.
God was, and always has been looking for faith. Once a person has faith, once a person truly hears what God is telling us to do and why, then a person can do good works.
God didn’t want dead animals; He wanted people with faith to see in the sacrifice of the dead animals the need for a blood sacrifice to atone. All of it was pointing to Christ, not the animal. God wanted faith in Christ, in the Messiah, the one who would come and suffer to make men right with God.
God didn’t want meticulously measured out spices as tithe; God wanted people to understand judgment, mercy and faith; do those first and then do the tithe.
It’s the same point Paul drives at in 1 Corinthians 13 and the same point Jesus makes in the Sermon on the Mount.
People have always been saved by grace through faith. Faith has always resulted in doing what God says. Doing what God says without faith is not doing what God says!
Behind all of these things is humility in the one believing and working. Good works without faith is merely pride. It doesn’t cut it with God.
“Will the Lord be pleased with thousands of rams, or with ten thousands of rivers of oil? shall I give my firstborn for my transgression, the fruit of my body for the sin of my soul? He hath shewed thee, O man, what is good; and what doth the Lord require of thee, but to do justly, and to love mercy, and to walk humbly with thy God?”