The Nahi (forbiddance) of ‘Uqood (contracts) and Tasarrufaat (conduct/disposal) for Ahkaam like trade and marriage are of two types:

1 – It can represent a Nahi (forbiddance) of the ‘Ain (essence) of the contract or the ‘Ain of the Tasarruf (conduct/disposal) itself which would make it Baatil or Faasid.

It would be Baatil if the Nahi (forbiddance) returned to the (essence of the) contract itself or to one of its Arkaan. That would indicate Al-Butlaan and this is like the Nahi of the Shaari’ in respect to selling Al-Maitah (carrion). That is because the Nahi returns back to a pillar of the contract and is contracted upon that in the case where the pillars of the contract are three: Al-‘Aaqid (the one who contracts), Al-Ma’qood ‘Alaihi (the matter being contracted upon) and Seeghat ul- ‘Aqd (the contract form).

This is like the Nahi (forbiddance) of Bai’ ul-Hisaah which is when a buyer throws a pebble and whatever one it hits he buys like if he was to throw it towards a pen of sheep for example. The Shaari’ (legislator) has forbidden this type of trade in itself and as such it would be Baatil because it represents a Nahi (forbiddance) in respect to the wording (or form) of the contract (Seeghat ul-‘Aqd). The contract or transaction would be Faasid if the Nahi returned back to a Sifah (attribute) from amongst its attributes and not to a Rukn from its Arkaan. This is like marrying two sisters at the same time. That is because the ‘Asl (origin) in respect to marrying each of the two sisters is permissibility in accordance to the Shar’a however what has been forbidden is for them to be married at the same time. It would therefore be Faasid and the rectification of this Fasaad would take place by divorcing one of them.