discord.js，如何获得原因

module.exports = {
  name : 'ban',
  description : ' ',
  async run(client, message, args, disc) {
    if(!message.member.hasPermission("KICK_MEMBERS")) return;
    const user = message.mentions.members.first()
    let length = args[1]
    let reason = args.slice(22).join(' ');

   if(!user) return message.channel.send('Please provide a user to ban')
   if(!length) return message.channel.send('Please provide a lenth to ban')
   if(!reason) return message.channel.send('Please provide a reason to ban')

   user.ban({
     days: length,
     reason : reason
   })
  }
}

我试图了解禁止用户的原因，但我不能。请帮我