1if(message.author.id === client.user.id) return;

1client.on('message', message => {
2  // this function can check whether the content of the message you pass is the same as this message
3  let filter = msg => {
4    return msg.content.toLowerCase() == message.content.toLowerCase() && // check if the content is the same (sort of)
5           msg.author == message.author; // check if the author is the same
6  }
7
8  message.channel.awaitMessages(filter, {
9    maxMatches: 1, // you only need that to happen once
10    time: 5 * 1000 // time is in milliseconds
11  }).then(collected => {
12    // this function will be called when a message matches you filter
13  }).catch(console.error);
14});