The household deciding about money.

Case: A householder, a trader of modest means, comes with two claims pulling at one purse. His daughter's wedding approaches; he has saved steadily toward it. Now his younger brother asks for that same sum, not as a loan but as a share in a trade venture, promising double in two years. The man cannot do both. He asks: whose claim comes first?

Sutra:
आगतं ऋणं पूर्वं, ततः लाभाशा।
Aagatam rnam poorvam, tatah labhaasha.
Meaning: A debt already come due comes first; after it, the hope of gain.

What I would do:
1. Count the wedding as a debt already owed. A promise made to a daughter is older than any venture; break it, and every future promise you make loses weight. Set that sum aside, untouched, before any talk of trade.
2. If you can spare only a part of the remainder, give that part to your brother's venture, but as a loan with a fixed share of profit, not as a silent partner's blind stake. Write it down plainly; kinship survives written terms better than unspoken hopes.
3. Tell your brother that the wedding comes first and that you are not refusing him — you are ranking him. Ask him to bring his accounts; if the venture is sound, you will consider a smaller sum next season, after the wedding costs are met. His respect for your order tells you more than his plan does.

A household is a small kingdom; its first law is that the king does not sell his own to buy a stranger's favour. Save the daughter's day, and your brother will still call you wise.