No weapon that is formed against you shall prosper; and every tongue that shall rise against you in judgment you shall condemn. This is the heritage of the servants of the Lord, and their righteousness which is of me, says the Lord. — Isaiah 54:17
I give eternal life to them. They will never perish, and no one will snatch them out of my hand. — John 10:28

Author
Charles Spurgeon
Summary: The enemy works diligently to forge weapons against the saints, but he could not do so without the Lord’s permission, and none of those weapons will prosper. Even more fearsome are tongues: slander, falsehood, insinuation, and ridicule can wound deeply and reach far. Though we cannot always silence them, God promises that they will not ruin us. Those who condemn us now will ultimately be condemned; their mouths will fall silent, and their falsehoods will ultimately bring honor to those who suffered them.
There is a great hammering in the enemy’s smithies and forges. They are making weapons with which to annihilate the saints. They could not even do that if the Lord did not permit them; for He has created the smith who blows the coals in the fire.
But see how diligently they labor! How many swords and spears they fashion! It does not matter, for on the blade of every weapon this inscription can be read: it shall not prosper.
But now listen to another noise: it is the strife of tongues. Tongues are more terrible instruments than those that can be forged with hammers and anvils, and the harm they inflict cuts deeper and reaches farther. What will become of us now? Slander, falsehood, insinuation, ridicule—these are poisoned arrows; how can we face them? The Lord God promises us that, if we cannot silence the tongues, we shall at least escape being ruined by them. They condemn us for the moment, but we shall condemn them in the end, and forever. The mouths of those who speak will be silenced, and their falsehoods will be turned to the honor of those good men who suffered because of them.
Source: The Cheque Book of the Bank of Faith. Translation by Allan Roman.
http://www.spurgeon.com.mx/chequera/meditames/noviembre.pdf