By default, if the SSH server you are connecting to is configured to accept password authentication, and you are not using a public key for passwordless authentication, there will be a prompt to enter the password.

~]# ssh john.doe@server1.example.com
john.doe@server1 password: 

This occurs, because, by default, the ssh command has PasswordAuthentication set to "yes". If you would like the SSH command to not produce the prompt for the password, you can use the following option.

ssh -o PasswordAuthentication=no john.doe@server1.example.com