Is the viscosity that remains after washing the anal exit, and which is not considered a palpable substance, pure or must it be removed by washing?

If the stickiness is not merely a doubt or a whisper [of Shaytan], then it must be removed by washing the exit until it becomes rough as it was before the excretion came out. This is the correct standard for purification with water (Istinja'), and the strong presumption of the removal of impurity suffices. However, if the stickiness is merely a whisper [of Shaytan], then it is not obligatory to wash it, and it is advised to turn away from such whispers.