'Deadly' in the Bible

they will pick up snakes. And if they drink any deadly [poison] it will never hurt them; they will lay hands on the sick and {they will get} well."

but no human being is able to tame the tongue. [It is] a restless evil, full of deadly poison.

And I will kill her children with deadly disease, and all the churches will know that I am the one who searches minds and hearts, and I will give to each one of you according to your deeds.