Psalm 19:7 The law of the Lord is perfect, converting the soul; The testimony of the Lord is sure, making wise the simple;
We must be very careful in understanding that the law of the Lord is not just the scriptures written down by Moses. It is not just the New Testament as live through by Jesus.
The law of the Lord is everything that God teaches us and all that we have before us from the prophets, disciples, apostles and everyone else who has contributed to it.
It is that law which will convict us from the inside. It is the truth that Jesus supported all through His ministry that will keep us going, giving us wisdom every step forward.