Data tag parsing failed: unbalanced quotation [duplicate]

When executing the following command, I get the error "Data tag parsing failed: unbalanced quotation"

/give @p leather_helmet 1 0 {display:{Name:"Nightslash Helm",Lore:["Legendary helmet found only in a secret hideout."]},ench:[{id:0,lvl:9999},{id:1,lvl:99999},{id:2,lvl:99999},{id:3,lvl:999999},{id:4,lvl:999999},{id:5,lvl:99999},{id:6,lvl:999},{id:7,lvl:99}],Unbreakable:1}

I don't see why the command would be wrong. What should I change for this error to go away?

If you're using standard Minecraft chat for this, it's not going to work, due to the character limit of the chat.

You'll have to run this command in a command block, that has a far, far higher limit.