Rule 21(d)(2) provides:
(d) GAMBLING.
(2) Any player, umpire, or Club or League official or employee, who shall bet any sum whatsoever upon
any baseball game in connection with which the bettor has a duty to perform, shall be declared
permanently ineligible.
Link: https://content.mlb.com/documents/8/2/2/296982822/Major_League_Rule_21.pdf