Revelation 9:13 YLT

¹¹  and they have over them a king -- the messenger of the abyss -- a name 'is' to him in Hebrew, Abaddon, and in the Greek he hath a name, Apollyon.

¹²  The first wo did go forth, lo, there come yet two woes after these things.

¹³  And the sixth messenger did sound, and I heard a voice out of the four horns of the altar of gold that is before God,

¹⁴  saying to the sixth messenger who had the trumpet, 'Loose the four messengers who are bound at the great river Euphrates;'

¹⁵  and loosed were the four messengers, who have been made ready for the hour, and day, and month, and year, that they may kill the third of men;