Istishab is a legal principle in Islamic jurisprudence (fiqh). It refers to the presumption of continuity or persistence of a previous state or condition unless there is evidence to the contrary. In other words, if something was considered permissible (halal) or prohibited (haram) in the past, it is assumed to remain so until there is evidence indicating a change.
For example, if a person was in a state of ritual purity (wudu) and there is no evidence to suggest that they lost that state (such as breaking wudu), the principle of istishab would maintain their state of purity.
This principle helps maintain stability and consistency in legal rulings unless there is clear evidence to alter the status quo. May Allah guide us in understanding and applying these principles correctly.