WCF 33.3.
As Christ would have us to be certainly persuaded that there shall be a day of judgment, both to deter all men from sin; and for the greater consolation of the godly in their adversity: (2 Pet. 3:11, 14, 2 Cor. 5:10–11, 2 Thess. 1:5–7, Luke 21:27–28, Rom. 8:23–25) so will He have that day unknown to men, that they may shake off all carnal security, and be always watchful, because they know not at what hour the Lord will come; and may be ever prepared to say, Come Lord Jesus, come quickly. Amen. (Matt. 24:36, 42–44, Mark 13:35–37, Luke 12:35–36, Rev. 22:20)