It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that the Prophet (peace and blessings be upon him) said: "Whoever intends to go to his wife and says: 'Bismillah, Allahumma jannibna al-shaytan wa jannib al-shaytan ma razaqtana' (In the name of Allah. O Allah, keep Satan away from us and keep Satan away from what You grant us), then if a child is decreed for the two of them, Satan will never harm it."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 12143