Question

you swore you'd never do nothing to hurt him.

Answer 1

You swore you'd never do nothing to hurt him.=You swore you'd never do anything to hurt him.你当时发誓 绝不做出任何伤害他的事.在一些方言中,人们常常用了两个或以上否定词,但仍然只有一个否定的意思.所以Michael Swan 在他的《英语用法指南》里说：

4 dialects

In many British,American and other dialects,two or more negatives can be

used with a single negative meaning.

I ain't seen nobody.(Standard English:I haven't seen anybody.)

I ain't never done nothing to nobody,and I ain't never got nothing from

nobody no time.(American song by Bert Williams)