One who has attempted to glue two things together knows that both surfaces must be clean before a proper bond can be forged.
أَيْضًا ،‏ تُهَدِّدُ ٱلنَّجَاسَةُ وَحْدَةَ ٱلْمَرْءِ مَعَ ٱللهِ وَمَعَ أَحِبَّائِهِ .‏