Jesus washes the disciples feet to teach them about humbleness and service. It is difficult to be proud when washing someone else’s feet, none of us are above serving others. God was glorified in Jesus’ actions, and we are called to do the same, “love one another: just as I have loved you”. This sort of love sets us apart from others, identifies us as disciples of Christ.
“Whoever has my commandments and keeps them, he it is who loves me.” We show Jesus’ love to each other by serving each other, but that love also involves belief in Jesus’ words and a genuine response to those words. By doing so, we know that God will love us, “he who loves [Jesus] will be loved by [Jesus’] Father.” That knowledge is a source of peace, a peace different from anything the world can offer. “Let not your hearts be troubled, neither let them be afraid.”