I apprehend, in the apostle's mind the phrase 'for my brethren' is connected with both 'pain in my heart' and 'a curse from Christ;' he parenthetically states how far his heart had gone for Israel, and then continues the phrase. This want of strict continuation of grammatical structure is very common with the apostle from the ardour of his style, and only adds force to what he says. He had loved them as much as Moses. (Ex. 32.32.) His pain was continuous: but the wish, 'to be a curse,' was like that of Moses, a moment's earnest appeal, as beside himself.
I have said 'that I might thus' because the word translated 'that' does not signify the ultimate end, but the means or way of doing it. The same word is translated 'so that' in the next clause.
As ch. 5.21, dikaiosune, and so to ch. 10.10.
'As of works.' Ek, here translated 'of,' is translated 'on the principle of' in chs. 1.17; 5.1; 9.32. But this sense is clearer here in having simply 'of' after the 'as,' and the sentence less encumbered.
Christ is the stumblingstone, as Paul goes on to explain.