It's challenging to provide an actual answer as you haven't provided enough details 🙂
Which firmware version do you have running? Assuming it is the "R" version since you said 'Layer3 configuration'.
Have you read the documentation for the firmware you are running? The docs are extensive, especially the 'command reference guide', and it is searchable.
While it isn't a direct answer, on my units running 9.x firmware I have:
management source-interface loopback 1 protocol ntp
I have the switch management IPs on the first loopback interface, and this command forces the NTP client to use the addresses of that interface as the source address for requests. This doesn't control the *outgoing* interface, though, that is controlled by the routing table when deciding how to route packets to the NTP servers that have been configured.