Now that I, your Lord and Teacher, have washed your feet, you also should wash one another's feet. (John 13:14)
I'm sure most of us are aware of the story of how Jesus washed the disciples' feet, right? They lived in a land where everyone wore sandals and you got dust all up in your toes whenever you were outside. So when you go to a person's house, their slave would wash your feet.
So of course when Jesus humbled himself to wash his disciples' feet, they were shocked, especially when they had just been debating which one of them was the greatest.
As a note, isn't it funny that Jesus had already done the big huge humbling of leaving the Godhead and becoming a mere human, and yet this little foot-washing thing just blew people's minds.
But the reason I only put that one specific verse up there is because I don't always remember reading it in the story. And I think we need to see this more often, because Jesus is very specificially telling us to serve each other. Yes, there are many many places where he discusses this (possibly because we're a bit thick?), consider this one more. Except for how insanely clear it is. This isn't a parable. It's a tiny bit of a similie, which means that we should apply the concept of serving to other things, but it also is specific to the disciples to literally wash each other's feet. There were times when they were places where no one liked them, where they would actually be called to shake the dust of a city off their feet. These were times that, if they had another person there with them, they would need to serve each other by washing each other's feet because no one else would.
And so we are called to serve one another, in what might seem the lowest forms of servitude, like washing one another's feet. But if we do it with a pure heart God will give us joy and peace and blessings. And besides, Jesus told us to do it.