How should one deal with the whispers of the devil with regard to doubting ablution and purity?

Entertaining doubts about ablution are from the devil, and so you should take refuge in God Almighty from the devil`s evil insinuations that aim to distort the religion. Once an organ is completely pure, do not question its purity because such insinuations do not mean that the purity is invalid as it has already been established.
And God Almighty knows best