Matthew 18:6-7

but whoever causes one of these little ones who believe in Me to stumble and sin [by leading him away from My teaching], it would be better for him to have a heavy millstone [as large as one turned by a donkey] hung around his neck and to be drowned in the depth of the sea. [Mark 9:42; Luke 17:2] “Woe (judgment is coming) to the world because of stumbling blocks and temptations to sin! It is inevitable that stumbling blocks come; but woe to the person on whose account or through whom the stumbling block comes! [Luke 17:1]