وما يحتمل السقوط فهو يسقط بالأداء أو بإسقاط الآمر
A duty that can lapse is discharged by performance or by the Lawgiver's removal of the duty.
A particular prayer obligation ends when the prayer is performed validly; this is discharge by performance. Simply omitting prayer is not performance, nor does inconvenience alone establish discharge.
Alternatively, the law may remove the duty under a qualifying circumstance. This is legal removal of the obligation. Both can bring that particular duty to an end, but they do so for different reasons.