Deuteronomy 11:28-29

28and a curse, if ye will not obey the commandments of Jehovah your 1God, but turn aside out of the way which I command you this day, to go after other 2gods which ye have not known.

29And it shall come to pass, when Jehovah thy 3God hath brought thee into the land whither thou enterest in to possess it, that thou shalt put the blessing upon mount Gerizim, and the curse upon mount Ebal.