Until the day in which he was taken up, after that he through the Holy Ghost had given commandments unto the apostles whom he had chosen.
Later it would include Paul.
The law and commandments of Christ are summed up in one word: the doctrine of Christ.
Whosoever transgresseth, and abideth not in the doctrine of Christ, hath not God. He that abideth in the doctrine of Christ, he hath both the Father and the Son.
It is given to us through His apostles, even as He gave the law to Israel through Moses.
Anything written in Scripture by the apostles after the resurrection of Jesus, is the law and commandments of Jesus, called the apostles' doctrine of Christ.
And they continued stedfastly in the apostles' doctrine and fellowship, and in breaking of bread, and in prayers.
If anything the apostles wrote to us after His resurrection sounds like a commandment to you, do it.
Ex:
And beside this, giving all diligence, add to your faith virtue; and to virtue knowledge; And to knowledge temperance; and to temperance patience; and to patience godliness; And to godliness brotherly kindness; and to brotherly kindness charity.
For if these things be in you, and abound, they make you that ye shall neither be barren nor unfruitful in the knowledge of our Lord Jesus Christ.
But he that lacketh these things is blind, and cannot see afar off, and hath forgotten that he was purged from his old sins.
This is commandment to us upon which our souls' depend. It's not optional.