'Custom' in the Bible

As she looked, there was the king standing by the pillar according to the custom. The commanders and the trumpeters were by the king, and all the people of the land were rejoicing and blowing trumpets. Athaliah tore her clothes and screamed “Treason! Treason!”

The settlers spoke to the king of Assyria, saying, “The nations that you have deported and placed in the cities of Samaria do not know the requirements of the God of the land. Therefore He has sent lions among them that are killing them because the people don’t know the requirements of the God of the land.”

Then the king of Assyria issued a command: “Send back one of the priests you deported. Have him go and live there so he can teach them the requirements of the God of the land.”

They feared the Lord, but they also worshiped their own gods according to the custom of the nations where they had been deported from.

To this day they act in accordance with their former [pagan] customs: they do not [really] fear the Lord, nor do they obey their statutes and ordinances, nor the law, nor the commandments which the Lord commanded the sons (descendants) of Jacob, whom He named Israel;

However, they would not listen but continued practicing their former customs.