Declarative rulings (aḥkām waḍʿiyyah)
Declarative rulings are the indicators instituted by the Lawgiver to affirm or negate something, or to declare it effective or void.
Among them are validity (ṣaḥḥah) and invalidity (fasād).

1 – Validity (ṣaḥīḥ)
Linguistically: sound, free from illness.
Technically: any act—devotional or contractual—whose legal effects arise upon its performance.

Valid worship is that by which liability is discharged and the obligation is lifted, while a valid contract is one whose legal consequences take effect, such as ownership passing through a sale.

Nothing is deemed valid unless all its conditions are fulfilled and all impediments are absent.
• An example in worship: performing the prayer within its appointed time, complete with all its conditions, pillars, and obligations.
• An example in contracts: concluding a sale that meets all the recognized conditions and is free of impediments.

If a single condition is missing, or an impediment is present, validity is eliminated.
• Missing a condition in worship: praying without purification.
• Missing a condition in contracts: selling what one does not own.
• Presence of an impediment in worship: offering an unrestricted voluntary prayer during a prohibited time.
• Presence of an impediment in contracts: a person obliged to attend the Friday congregational prayer selling something after the second call to prayer in a manner that is not lawfully permitted.