Call service node Data inject msg.payload

#1

I'm using a call service node to call alexa_tts. I want her to say the string from the msg.payload from the previous node.
A working Data field looks like this:
{"message":"This is a test"}
How do i replace "This is a test" with the string in the payload from the calling Node?

#2

Got an answer on the HA Forum:
{"message":"{{payload}}"}