1. The person taking the oath must be b¡ligh and sane, and should take the oath consciously and volitionally. Therefore, the act of taking an oath by a minor, an insane person, an intoxicated person, or a person who has been compelled is not valid. The same will apply if a person unconsciously takes an oath in a moment of anger. The oath taken by a bankrupt or feeble-minded person is not valid in the event that it necessitates the disposal of their property.
2. The act for which one takes an oath should not be a makruh or a forbidden act. Similarly, the act that one takes an oath to refrain from should not be an obligatory or recommended act. To claim the obligation of an act which is the subject of an oath to perform or refrain from a canonically neutral act which does not possess any worldly or religious benefit is problematic.
3. A person should take the oath by one of the names of the Lord that is exclusively reserved for His Holy Essence, such as God or Allah. Similarly, if a person takes an oath by a name that is also used to refer to someone other than God, but it is so frequently used to refer to God that whenever it is employed, the Holy Essence of the Lord is evoked in the mind, such as taking an oath by the name the Creator or the Sustainer, it too will be valid. In fact, if he takes an oath using a name that is used to refer to God and someone other than Him, but intends to refer to God, obligatory precaution dictates that he act according to that oath.
4. He should pronounce the oath verbally. Hence, if he writes it down or intends it in his heart, it will not be valid. However, if a person who is unable to speak takes an oath by hand signing, it will be valid.
5. He should be capable of fulfilling the oath. If he is able to perform it upon taking the oath, but is rendered incapable later on, his oath will be void from the moment he became incapable of fulfilling it. The same applies if fulfilling the oath, vow or pledge entails such hardship, that it is not possible to bear it.
The oath by a person who suffers from uncertainty.