Ibn Abbas narrated that:
The Messenger of Allah said: "If anyone of you, when having sexual intercourse with his wife, says: (Bismillah, Allahumma jannibnash-Shaitana wa jannibish-Shaitana ma razaqtana) 'In the Name of Allah, O Allah! Protect me from Shaitan and protect what you bestow upon us from Shaitan' - then if Allah decrees that they should have a child, Shaitan will not be able to harm him.'"