Permissions 0644 for ‘/home/user/.ssh/id_rsa’ are too open.

$ git clone git@github.com:xyou365/AutoRclone.git
Cloning into ‘AutoRclone’…
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ WARNING: UNPROTECTED PRIVATE KEY FILE! @
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Permissions 0644 for ‘/home/user/.ssh/id_rsa’ are too open.
It is required that your private key files are NOT accessible by others.
This private key will be ignored.
Load key “/home/user/.ssh/id_rsa”: bad permissions
git@github.com: Permission denied (publickey).
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.
$ chmod 0400 /home/user/.ssh/id_rsa