"I divorced my wife when she was menstruating. 'Umar mentioned that to the Messenger of Allah and he said: 'Tell him to take her back until she becomes pure (i.e., her period ends), then she has her period (again), then she becomes pure (again), then if he wishes he may divorce her before having sexual relations with her, and if he wishes he may keep her.
The one who tries to follow the Prophet صلى الله عليه وسلم in the acts of `Ibaadaat should also follow him in respect to time, place, reason, form, characteristic and number (of times). So, if a person says “Maa shaa’ Allaah” for preventing the evil-eye, then he has not followed the Sunnah of the Prophet صلى الله عليه وسلم in respect to “the reason”.