'Forsook' in the Bible

Then men will say, ‘Because they forsook the covenant of the Lord, the God of their fathers, which He made with them when He brought them out of the land of Egypt.

But Jeshurun waxed fat, and kicked: thou art waxen fat, thou art grown thick, thou art covered with fatness; then he forsook God which made him, and lightly esteemed the Rock of his salvation.