Respectfully Elder, Jesus told the disciples in
Jn 13:15 I have given you an
example
He had asked them in vs 12 Do you know aht I have done to you?
The obvious answer was that he had washed their feet, but that was ONLY an example they in that culture could relate to. his lesson was deeper that.
The lesson he was teaching is that the greater should serve the lessor in all things, not just a mere washing of the feet that was practiced by most in that era, but to always be in humble submission to our brothers.
Jesus taught in parables, EXAMPLES. He did this to get his point across.
His washing of the disciples feet was just that, an
example as vs 15 states.
If you think he was making a custom of that time, a binding sacrament of the church, I think you have missed the object lesson Jesus gave the disciples recorded in
John 13.
Hope maybe some day you might see the lesson there. Because I think that binding things upon NT Christians as salvational that are not salvational will get you in a bit of trouble when we all give a reckoning.