Joel 2:29-32

At that time I will pour out my Spirit also on male slaves and female slaves. I will show miracles in the sky and on the earth: blood, fire, and thick smoke. The sun will become dark, the moon red as blood, before the overwhelming and terrible day of the LORD comes. Then anyone who calls on the LORD will be saved, because on Mount Zion and in Jerusalem there will be people who will be saved, just as the LORD has said. Those left alive after the day of punishment are the people whom the LORD called.