أو كان كافراً في أول الوقت مسلماً في ذلك الجزء، أو كانت حائضاً أو نفساء في أول الوقت طاهرة في ذلك الجزء وجبت الصلاة
If Islam or the end of a relevant ritual excuse occurs in the pertinent portion of time, the prayer obligation can arise.
A status existing at the beginning does not invariably determine the entire period. If legal capacity and the conditions for an obligatory prayer exist within the relevant portion, a duty can attach.
The precise minimum time and detailed purification rules require their own juristic conditions. The principle taught here is the relation between an existing cause and the emergence of legal accountability.