Secrets Manager resource policy: "This resource policy contains a syntax error"

Question

I want to add Resource Permissions on my Secrets Manager secret and I have this syntax error:

This resource policy contains a syntax error

Can anyone help me? This is the policy:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Principal": {
                "Service": "secretsmanager.amazonaws.com"
            },
            "Action": "lambda:InvokeFunction",
            "Resource": "..."
        }
    ]
}