Don't you mean ""I lay down my life only for My sheep?"
"Only" is superfluous. But let's look at the scripture in its context anyway.
Jesus is explaining to unbelieving Jews who He is and what He is doing by using an analogy of the shepherd and his sheep, and that relationship. In John 10:1-6 He says it one way and they could not understand Him so He said it another way in verses 7-18. He is the door (verse 7) and if anyone enters that door, they will be saved. All others beside Him are thieves and robbers seeking to kill and destroy. (vv8-9). But Jesus is the good shepherd. The good shepherd lays down His life for the sheep, compared to the hired hand, not a shepherd, who does not own the sheep, runs away, leaving the sheep to the wolves who snatches and scatters them. Jesus the good shepherd is willing to die to save the sheep. (vv10-13)
And then Jesus says a curious thing in verse 14. He says, "I know my own and my own know me." Now, this is a direct correlation to what He has already said and what He is about to say that is compared to a literal truth concerning literal sheep. They truly will not follow the voice of a shepherd they do not know, and they truly literally will follow the voice of the shepherd they know. That is the nature of sheep. It is true that no doubt very few people today know this or anything about sheep, and therefore miss the depth of what He is saying, but Jesus' hearers lived in an agricultural culture and knew it very well.
In verse 15 Jesus compares this relationship between Him and His sheep to that of how the Father knows Him and He knows the Father. Then He says that He has other sheep not of that fold (which would be Israel as that is who He was talking to) and the ones not of that fold would be Gentiles, and they would all be one flock. We know this from the results as told and demonstrated by the apostles, and in accordance with OT prophecy. In verses 17-18 Jesus says that is why the Father loves Him, because He lays down His life, that He may take it up again. This is what the Father sent Him to do, and this is what He is going to do. What? Die for those sheep, rise again from the dead defeating the enemies of the sheep, giving them life.
The Jews, not liking this, began to be divided because of His words. They obviously understood what He was saying in part. Some said He had a demon and was insane. Others remembered His miracles and said how can he have a demon and open the eyes of the blind.They did know only God could do that. (vv19-21)
Jesus was walking in the temple and Jews gathered round Him and demanded that they tell them plainly, not in parables and such but yes or no, are you the Christ? (vv22-24)
25. Jesus answered them, "I told you, and you do not believe. The works that I do in my Father's name bear witness about me, 26 but you do not believe because you are not among my sheep" Here He begins to say what he said twice before in yet a different way. (I can surely relate!) 26. "but you do not believe because you are not among my sheep. 27. My sheep hear my voice, and I know them, and they follow me. 28 I give them eternal life, and they will never perish, and no one will snatch them out of my hand. 29. My Father, who has given them to me, is greater than all, and no one is able to snatch them out of the Father's hand. 30. I and the Father are one."
31. The Jews picked up stones again to stone Him." Don't be as they were and pick up stones to throw because you cannot or will not believe what Jesus said in these passages.
Only His sheep hear His voice, and they were always His sheep. They did not become His sheep. When they heard His voice, they followed Him. They were given to Him by the Father before the foundation of the world, and He went to the cross to rescue them from the wolves. And it is His sheep that He laid down His life for. Not all the sheep in the whole world and for all time.
