Occasional fasts
But besides those which were fixed, in every nation fearing God there have always been occasional fasts, appointed from time to time as the particular circumstances and occasions of each required. So when the children of Moab and the children of Ammon came against Jehoshaphat to battle, Jehoshaphat set himself to seek the Lord and proclaimed a fast throughout all Judah (2 Chronicles 20:1-3). And so in the fifth year of Jehoiakim the son of Josiah, in the ninth month, when they were afraid of the king of Babylon, the princes of Judah proclaimed a fast before the Lord to all the people of Jerusalem (Jeremiah 36:9).
1771 text
But beside those which were fixt, in every nation fearing God, there have always been occasional fasts, appointed from time to time, as the particular circumstances and occasions of each required. So when the children of Moab and the children of Ammon, came against Jehoshaphat to battle; Jehoshaphat, set himself to seek the Lord, and proclaimed a fast throughout all Judah. And so in the fifth year of Jehoiakim, the son of Josiah, in the ninth month, when they were afraid of the king of Babylon, the princes of Judah proclaimed a fast before the Lord, to all the people of Jerusalem.