Teferi's abilities don't limit what you can target with Finale of Promise. However, if an opponent of yours controls Teferi, you can't cast any spell while Finale of Promise is resolving, even if it's your main phase, since Finale of Promise would still be on the stack at that time (C.R. 117.4, 608.2c, 307.5, 101.2; see also C.R. 117.1a, 601.3, 608.2f). See also this thread.
EDIT (Sep. 14): Edited, including because some rules were renumbered with Core Set 2020.
EDIT (Oct. 1, 2020): Edited.
Opponent controls a Teferi. I play a Finale of Promise targeting an instant and a sorcery.
How does this work out? Can I only target one?
Thanks
EDIT (Sep. 14): Edited, including because some rules were renumbered with Core Set 2020.
EDIT (Oct. 1, 2020): Edited.