ANSWER:
I do not know of any basis for that. Rather what is prescribed for the one who finishes doing wudoo’ is to say: “Ashhadu an laa ilaaha ill-Allah wahdahu laa shareeka lah wa ashhadu anna Muhammadan ‘abduhu wa rasooluhu. Allaahumma aj’alni min al-tawwaabeen waj’alni min al-mutatahhireen (I bear witness that there is no god except Allah alone with no partner or associate, and I bear witness that Muhammad is His slave and Messenger. O Allaah, make me one of those who repent and make me one of those who purify themselves).”