At "End Times", there are 2 opportunities to give up source:
1. Before fight start, Dallis will ask. If we choose to surrender here, we fight along side Lucian and Dallis against Braccus. We accept our fate as silent monks.
2. Not accepting the above, fight Lucian, Dallis and Braccus. After winning, choose to become divine, then additional choices come up, giving up all source to seal the veil is one of them.
I am referring to the second one above. In my first play through, because of Lucian explanation, I thought I will become the fake divine and my teammates will be fine. But hell no, we became silent monks and Lucian back to his throne. I was like WTF !@#$%
I finished 4 play through but this just keep coming back to my mind. I never choose that again in my other play through.