In Jn 13:17 Jesus said, “If ye know these things, happy are ye if ye do them.”  “These things” that he wanted them to know are found in the context.  The context is Jesus washing the feet of his disciples, among whom was Judas Iscariot, Jn 13:2, 10-11, 21.  He washed their feet as an example to them, that they should do as he did, Jn 13:15.  

Then he said, “The servant is not greater than his lord; neither he that is sent greater than he that sent him,” Jn 13:16.  Jesus was their Lord, Jn 13:13, and they were certainly not greater than he was.  And Jesus was the one who was sent, and he was certainly not greater than his Father who sent him.  And so he washed their feet, not because he was their servant, but because he was his Father’s servant.  

First, you must know these things.

When Jesus said, “If ye know these things,” he wanted them to know that they were all on the same level since they were not greater than their Lord.  They had already had trouble with who among them would be the greatest, Mk 10:35-45.  Jesus had to teach them that the greatest is the servant, he is the minister.  We must know that none of us is greater than the others of us because we are all under the Lord.  That’s the lesson.

Therefore, we should serve because we are not greater than Jesus, and he served.  We must know “these things.”  

Look how Paul followed this example in his ministry.  In 1 Cor 9:19, Paul said, “For though I be free from all men, yet have I made myself servant unto all, that I might gain the more.”  In 2 Cor 4:5, he said, “For we preach not ourselves, but Christ Jesus the Lord; and ourselves your servants for Jesus’ sake.”  Did you see that?  He said, “… ourselves your servants for Jesus’ sake.”  Paul knew “these things.”  He was the apostle of the uncircumcision; he was the apostle chosen by the Lord; but he was the servant of the Lord Jesus Christ, and therefore, the servant of all, for the Lord’s sake.  That’s how he could serve men, and yet not “please men,” Gal 1:10; 1 Thes 2:4.  He was serving men to please the Lord.  This is what we have to know.  If you serve others with the goal of trying to please them, you won’t be the servant of Christ.

Then you must do these things.

Just knowing these things is not enough to make you happy.  Doing them is what brings the happiness.  Jesus said, “happy are ye if ye do them.”  When you serve others for the Lord’s sake, look at the joy that follows.  In Phil 2:17, Paul said, “Yea, and if I be offered upon the sacrifice and service of your faith, I joy, and rejoice with you all.”  Look at the exceeding joy he experienced serving the Corinthians in 2 Cor 7:3-4, and serving the Colossians, Col 1:23-25. 

Jesus said that there is joy and happiness when you know these things and do them.  You should prepare your heart before the Lord with this lesson and then you should start serving others.  This generation and society is self-serving.  People often go to church for what they can get out of it.  Be of a different mindset.  Look for ways to serve.

Conclusion: If you have never known this happiness and joy, you have either not learned the lesson that Jesus taught his disciples by example, or you have not done these things.  If you want to be happy, start serving others for the Lord’s sake.  You will find joy and happiness.