The phrase “at that day” generally refers to the last days and Jesus’ second coming. To their great joy and salvation, the righteous will be visited with the voice of the Lord God. Others will be visited with a different voice of God (D&C 88:88–90), actually various natural catastrophes, what we call “acts of God”—thunderings, lightnings, tempests, fires, smoke, vapors of darkness, and earthquakes—as a testimony against them.