Jesus didn't "say" a whole lot to His disciples about serving one another. "They" would have a LOT to say about it in their later writings, but Jesus didn't say much. Instead, He modeled it. Serving the physical, emotional, spiritual and felt needs of the people He came in contact with. It wasn't until the night He was to be betrayed, when He washed the feet of Judas that He gave them the command, serve each other as I have served you. It's out command too.