How to apply a filter on events before it gets into Splunk Indexer from ServiceNow based of particular field value ?

I am using "Splunk app for Servicenow" & "Splunk add-on for ServiceNow" which is integrated with ServiceNow. I want to extract only those incidents in Splunk indexer (snow) from ServiceNow where "assignment_group" = "XYZ" or "ABC" Currently it is extracting million of events in Splunk from ServiceNow Incidents.