What constitutes the boundary for breaking continuity (mualah)?
Chapter on the Obligation of Purification
Al-Mughni
Book of Purification
Primary text
The obligatory continuity means that one must not leave off washing a limb until a period has passed during which the preceding limb would dry in temperate weather. This standard is set because the drying time of a limb can vary depending on the time. This consideration is to be made between the beginning and end of the purification rite.
Supporting text
Another narration from Ibn Aqil suggests that the excessive separation that invalidates the wudu is that which is considered egregious by custom, as the Sharia has not defined a specific measure, requiring reference to common practice, similar to concepts of possession or separation in sales contracts.