What was the specific business proposition that Damu Anna received, and how did it affect him?

As detailed in Chapter 25, Damu Anna received a letter from a friend in Mumbai proposing a joint venture in the cotton trade. The friend outlined a plan to buy cotton, anticipating that its price would rise instantly. He claimed this "clean and safe" business would yield a net profit of two lakh rupees, which would be split evenly between them, with each earning a lakh. The friend urged a quick reply, warning that those who don't act on such opportunities repent later. This proposal caused Damu Anna significant mental distress, putting his mind in a turmoil as he deliberated on the risky but potentially lucrative offer.