No prompt for ssh passphrase
In the ~/.ssh/config, add these lines:

Host *
    UseKeychain yes
    # automatically add keys to keychain
    AddKeysToAgent yes


UseKeychain yes will use any saved ssh keys in the Mac Keychain.

AddKeysToAgent yes will automatically save ssh keys in the Mac Keychain after the first time you enter the passphrase. If you don't add this, you can use ssh-add -K to manually add keys to the keychain also.

Note: These options were added since macOS 10.12.2

https://developer.apple.com/library/archive/technotes/tn2449/_index.html