John 21:20-25 Then Peter, turning about, sees the disciple whom Jesus loved following; which also leaned on his breast at supper, and said, Lord, which is he that betrayed thee? Peter seeing him said to Jesus, Lord, and what shall this man do? Jesus said unto him, If I will that he tarry till I come, what is that to thee? follow thou me. Then went this saying abroad among the brethren, that that disciple should not die: yet Jesus said not unto him, He shall not die; but, If I will that he tarries till I come, what is that to thee? This is the disciple which testified of these things, and wrote these things: and we know that his testimony is true. And there are also many other things which Jesus did, the which, if they should be written every one, I suppose that even the world itself could not contain the books that should be written. Amen. 

‘The disciple whom Jesus loved’ the last of five times, referring to John (13:23; 19:26; 20:2; 21:7, 20, 24). He was not loved more than others by Christ, but he accepted His love and chose to call himself accordingly. God does not have respect for persons, with regards to their looks, races, classes and sexes (Acts 10:34; Rom. 2:11; Gal. 3:28; Jas. 2:1-4).

‘Lord, which is he that betrayed thee? … what shall this man do? … If I will that he tarries till I come, what is that to thee?’ Peter had his instructions; now he wanted to know what John was supposed to do. Jesus rebuked his curiosity by stating that if He wanted John to live to the second coming that was none of his concern. He told Peter to follow Him and let John do likewise. This statement about John not dying is explained in John 21:23. He did die about the close of the first century after he finished the book Revelation on the isle of Patmos (Rev. 1:9).

‘This is the disciple which testified of these things, and wrote these things’ this is proof of the authorship of John. ‘Many other things which Jesus did, the which, if they should be written every one, I suppose that even the world itself could not contain the books that should be written.’ This verse simply expresses the idea that Jesus had done so many things which are not written, that if they should be written in books the world (Greek word kosmos: social world) would not have room for them. Men would not even take time to examine or digest them.