Harman /Kardon Citation Oasis Manual Del Usuario página 13

Set the sleep timer for music playback
Desired Action
Set a sleep timer during music playback
Set a sleep timer before music playback
Note:
The Sleep timer function is now available for Chromecast built-in and Bluetooth music streaming. For FM, AUX and AirPlay music streaming, this feature may be
available in the future via automatic software updates.
Voice Command
(Say "Hey Google", then...)
"Set a sleep timer for 30 minutes" / "Set a sleep timer at 9:30"
"Play some music for 30 minutes"