Partnership (shirkah)

A partnership is the answer riba is not. Reward is earned by sharing risk, not by guaranteeing a return. The governing maxim is al-ghunm bi-l-ghurm: entitlement to gain is tied to bearing loss. So the same two rules recur across this family. No partner’s capital is guaranteed, and loss follows capital. Profit may follow an agreed ratio, yet loss cannot be escaped. Guarantee a partner whole, win or lose, and the partnership is a loan in costume that will not compile.

Note

Citations are [scholar-verify]; the engine proves consistency, not a fatwa. Whether profit must track capital, or may be stipulated freely, is a live khilāf the rule modules model: the Mālikī and Shāfiʿī modules require profit_tracks_capital, the Ḥanafī and Ḥanbalī do not.

Mushārakah (musharakah)

A full partnership (sharikat al-ʿaqd). Partners pool capital. Profit is shared by a pre-agreed ratio, which may differ from the capital ratio, but loss is borne strictly by capital share, and no partner guarantees another’s capital. Al-ribḥ ʿalā mā shtaraṭā wa-l-waḍīʿa ʿalā qadr al-māl.

Code	What it guards
PROFIT-1	profit is split by ratio; a fixed guaranteed sum to either party is riba.
RISK-1	loss follows capital share (no risk-sharing means no partnership).
RIBA-1	capital_guarantee is none.
CAP-1 / CAP-2	capital sums to exactly 10000 bps, across at least two contributors.

musharakah.fiqh: consistent

capital {
  partnerA : 6000 bps;
  partnerB : 4000 bps;
  require partnerA + partnerB == 10000 bps;
}
returns {
  profit { split: ratio; partnerA: 5000 bps; partnerB: 5000 bps; }  // ratio may differ from capital
}
risk {
  loss: proportional_to_capital;   // loss strictly by capital share
  capital_guarantee: none;
}

Diminishing partnership (musharakah_mutanaqisah)

The home-finance workhorse. The financier and the client co-own an asset; the client buys out the financier’s share over time while paying rent on the financier’s living share. It was the original instrument, and it carries the full apparatus: an independent valuation oracle, a rent that prices the share rather than the principal, and an oracle-attested buyout price.

Code	What it guards
RIBA-1 / RISK-1	capital not guaranteed; loss proportional to ownership.
RIBA-2	rent prices the living share or usufruct, not the principal.
RENT-1 / RENT-2, BUYOUT-1 / BUYOUT-2	a rent and a diminishing-buyout mechanism both exist and are well-formed.
GHARAR-1	the buyout price is oracle-derived; a self-named or fixed price reintroduces gharar.
ROLE-1 / ROLE-2	an independent valuation oracle party exists.
INV-1	the required invariants are declared (ownership_conserved, rent_on_living_share, loss_follows_capital, price_attested).
MAQASID-2	(warning) if the rent is, in substance, calibrated to amortise capital at a fixed yield, it drifts toward a disguised loan, and a scholar should review it.

The full diminishing-partnership spec appears in Getting started, and its zakat- and aṣnāf-extended form in Charge.

Muḍāraba (mudarabah)

Profit-sharing trust financing. Capital comes from the rabb al-māl alone (100%); the muḍārib contributes labour, not capital. Profit is shared by a pre-agreed ratio. Financial loss falls on the rabb al-māl alone, since the muḍārib loses only his effort, absent proven taʿaddī or taqṣīr. The realized return must be attested by an independent oracle, not self-reported by the muḍārib.

Code	What it guards
MUD-1	the muḍārib contributes no capital (capital above zero makes it a mushārakah).
MUD-2 / MUD-3	both roles, rabb_al_mal and mudarib, are present.
MUD-4	the rabb al-māl funds 100% (10000 bps).
RISK-2	loss is on the rabb al-māl alone.
RIBA-1	no guaranteed capital or profit.
PROFIT-1 / PROFIT-2	profit split by ratio; a profit mechanism exists.
GHARAR-2	realized profit is oracle-attested, not self-reported.

mudarabah.fiqh: the load-bearing terms

capital { rabb: 10000 bps; agent: 0 bps; require rabb + agent == 10000 bps; }
returns {
  profit {
    source: oracle.realizedProfit;   // realized value attested independently (anti-gharar)
    split:  ratio;                   // pre-agreed ratio, never a fixed sum (anti-riba)
    rabb: 6000 bps; agent: 4000 bps;
  }
}
risk { loss: on_rabb_al_mal; capital_guarantee: none; }

Muḍāraba pool (mudarabah_pool)

The investment fund. Many rabb al-māl form a pool that provides the capital, and one muḍārib manages it. Profit is shared by an agreed ratio between the muḍārib and the pool; loss falls on the capital pool pro-rata; the muḍārib guarantees nothing. This is the first place the compiler steps past the bilateral ʿaqd into the multilateral.

Code	What it guards
POOL-1 / POOL-2	the rabb pool shares total 10000 bps, with at least two participants.
RISK-2	loss is borne by the capital pool (on_capital_pool).
RIBA-1	the muḍārib guarantees nothing.
PROFIT-1	profit split by ratio.

mudarabah_pool.fiqh: many rabb al-māl, one muḍārib

pool { rabbA: 5000 bps; rabbB: 3000 bps; rabbC: 2000 bps; }
returns {
  profit { split: ratio; mudarib: 3000 bps; rabbs: 7000 bps; }
}
risk { loss: on_capital_pool; capital_guarantee: none; }