New Revised Standard Version
But I will warn you whom to fear: fear him who, after he has killed, has authority to cast into hell. Yes, I tell you, fear him!

Contemporary English Version
God is the one you must fear. Not only can he take your life, but he can throw you into hell. God is certainly the one you should fear!

New American Bible
I shall show you whom to fear. Be afraid of the one who after killing has the power to cast into Gehenna; yes, I tell you, be afraid of that one.

Douay-Rheims Bible
But I will shew you whom you shall fear: Fear ye him who, after he hath killed, hath power to cast into hell. Yea, I say to you: Fear him.

But I will shew you whom you shall fear: Fear ye him who, after he hath killed, hath power to cast into hell. Yea, I say to you: Fear him.

forewarn.

Mark 13:23 Take you heed therefore: behold, I have foretold you all things.

1 Thessalonians 4:6 And that no man overreach nor circumvent his brother in business: because the Lord is the avenger of all these things, as we have told you before and have testified.

Fear.

Proverbs 14:26 In the fear of the Lord is confidence of strength, and there shall be hope for his children.

Jeremiah 5:22 Will not you then fear me, saith the Lord: and will you not repent at my presence? I have set the sand a bound for the sea, an everlasting ordinance, which it shall not pass over: and the waves thereof shall toss themselves, and shall not prevail: they shall swell, and shall not pass over it.

Jeremiah 10:7 Who shall not fear thee, O king of nations? for thine is the glory: among all the wise men of the nations, and in all their kingdoms there is none like unto thee.

Revelation 14:7 Saying with a loud voice: Fear the Lord and give him honour, because the hour of his judgment is come. And adore ye him that made heaven and earth, the sea and the fountains of waters.

Revelation 15:4 Who shall not fear thee, O Lord, and magnify thy name? For thou only art holy. For all nations shall come and shall adore in thy sight, because thy judgments are manifest.

power.

Psalm 9:17 The wicked shall be turned into hell, all the nations that forget God.

Matthew 10:28 And fear ye not them that kill the body, and are not able to kill the soul: but rather fear him that can destroy both soul and body in hell.

Matthew 25:41,46 Then he shall say to them also that shall be on his left hand: Depart from me, you cursed, into everlasting fire, which was prepared for the devil and his angels. . . .

2 Peter 2:4 For if God spared not the angels that sinned, but delivered them, drawn down by infernal ropes to the lower hell, unto torments, to be reserved unto judgment:

Revelation 20:14 And hell and death were cast into the pool of fire. This is the second death.