Feast of Tabernacles

Zechariah 14
16 ¶ And it shall come to passe that euery one that is left of all the nations which came against Ierusalem, shall euen goe vp from yeere to yeere to worship the King the Lord of hostes, and to keepe the feast of Tabernacles.
17 And it shall be, that who so will not come vp of all the families of the earth vnto Ierusalem, to worship the King the Lord of hostes, euen vpon them shall be no raine.
18 And if the family of Egypt goe not vp, and come not, that haue no raine: there shall bee the plague wherewith the Lord will smite the heathen that come not vp to keepe the feast of Tabernacles.
19 This shall be the punishment of Egypt, and the punishment of all nations that come not vp to keepe the feast of Tabernacles.

During the tribulation that comes on the nations (talked about in the book of Revelation), that is after the sign of the son of man, after that Israel has been made head of the nations and before the second coming of the lord Jesus Christ, then shall the nations go up to Israel to worship and keep the feast of tabernacles in order to get rain in their nation.