From Jubair bin Nufair who said that he heard Abu ad-Dardaa, while he was at the end of his prayer, having finished the tashahhud, seeking refuge in Allaah from nifaaq (hypocrisy), and he exceeded in seeking refuge from it. So Jubair said: And what is it with you O Abu ad-Dardaa, and with nifaaq? So he said: Leave us alone, leave us alone. For by Allaah, a man turns away from his deen in just a single hour, and so he becomes totally devoid of it (i.e. loses it altogether).” (Siyar A’laam in-Nubulaa 2/383 and ad-Dhahabee said “Its Isnaad is Saheeh”.).
Quoted from “Imaan Builder 4: The Observance of Sincerity in One’s Speech and Action,” accessible via SalafiPublications.com, and Allah knows best.