ومن حكمه: أنه لا يتأدى المأمور به إلا بنية معينة.
A time-bound duty of this container type is not properly discharged without an intention specifying the required act.
A prayer period admits obligatory, make-up, and voluntary prayer. Standing, bowing, and prostrating do not alone identify which particular prayer was performed. Specific intention distinguishes one legal act from the other acts that remain possible.
For example, four units during ẓuhr time do not automatically constitute that day's obligatory ẓuhr prayer. The intention and relevant conditions must identify the act.
In this context intention does more than express sincerity: it legally identifies the particular act being discharged.